AdButler offers a free remotely-hosted banner management service wherein they take just 7.5% of your inventory to promote their advertisers in order to cover the costs of the service. Publishers are provided with real-time reporting, quite a few management/targeting options and even the ability to run multiple domain accounts under the one system.

ad-rotator.com is a remote ad management system that supports both free (limited) and premium accounts. The service boasts an intuitive tool set. Some features include rotation of weighted ads, detailed visitor info, frequency caps, geo-targeting, advertiser accounts, pop-up/under code and support for both text links and custom ad sizes.

Matt's Script Archive offers a collection of free-to-use CGI/Perl scripts which you can download and implement onto your pages. His Random Image Displayer and SSI Random Image Displayer can both be used to rotate advertiser's banners throughout your site.

Orbit Cycle presents web publishers with an easy solution to managing their banner ad space affordably. This service is free to join, and allows publishers to rotate ads on their site(s) without the trouble of installing and maintaining complex scripts. The rotation system is remotely hosted by Orbit Cycle, but still provides a reasonable level of flexibility, while supporting publisher and advertiser stat checks in real-time. The service costs you nothing to use, but Orbit Cycle reserves the right to use 10% of your ad space to promote themselves and their own advertising partners in order to subsidise the tech costs.

phpAdsNew is a banner management and tracking system developed in PHP. This free script can, out of the box, support multiple ad sizes and provide stats to both the publisher and advertising clients (including reports automatically sent by email). Many hacks are available for this script on the SourceForge site, which further extends its functionality.

Ad Cafe is a simple-to-use but effective ad campaign manager that is equipped with the power to automatically draw from your ad pool to publish, target, track and manage up to hundreds of banners - without requiring any extensive CGI or HTML knowledge on behalf of the webmaster. They have an online demo for you to try out before purchase to see if the package suits your needs. Ad Cafe costs $79.95 to purchase and Ad Cafe Pro costs $295.95.

AdCycle is an ad serving solution reportedly created by the founder of ad network FastClick. It offers an extraordinary range or tracking, targeting and delivery options to publishers. The system supports the ability to weigh campaigns and individual banners within campaigns, so as to best optimize your response ratios. Campaigns may be set to expire according to time, impressions or clicks delivered, and your advertisers all have the ability to access their password-protected stats that track the performance of their banners in real-time. Most rich-media formats are supported, as is the rich-media code supplied by ad networks such as Engage Media and Burst!, enabling you to effectively run these ads as defaults when your direct-sold campaigns have expired. AdCycle is relatively svelte, and doesn't place undue strain on your server. If you intend to serve in excess of 100,000 impressions/day, though, you should look into the FastCGI version of the script (which is free). Otherwise, the regular $89 shareware license (30 day free trial) is for you. Requires MySQL. Highly recommended. (This is the script that I use on Net-Ads.com)

AdGenie offers a plethora of advanced features with its Rotating Banner Ads Management Program. Users can upload banners to the AdGenie system and specify when the banner should be shown, when and for how long, as well as who should see the ad (based on a number of criteria, including search requests). You can demo the AdGenie layout and find out about most of its features HERE. AdGenie costs $295 to purchase.

Ad Juggler is a feature-packed, commercial strength ad management system with a hassle-free point-and-click interface. It has the capacity to track and manage multiple banner pools, monitoring and producing both impression and click-through statistics, which you may recieve via email reminders. The Ad Juggler Classic license is priced at $795, which is valid for one domain only, but which includes all the necessary upgrades for 6 months after purchase. Professional, Enterprise and Hosted versions of this software are also available, adding to the suite's scalability.

AdRevolver is a competitively priced, multi-platform ad management system available both as a stand-alone product and as hosted service solution. Provides detailed tracking and statistics, plus precise targeting according to geography, category and other variables. Supports rich-media creatives. Tested at 200+ million monthly impressions per CPU. A banner exchange solution for networks is readily available.

ADvantage is a professional-quality banner management and rotation package which has the ability to manage multiple banner pools and even multiple sites. It's web-based interface and real-time custom reporting features make it easy to use, despite its advanced features. A free demo is available online and, strangely, their 'purchase' page is under construction, but you may order their package for 'under $1000' by calling 954-370-0025.

Be Free has produced a system called 'BFAST', which allows Webmasters of commercial sites the opportunity to establish a commission, or 'affiliate', banner program. This enables sites to maximise their sales by paying other webmasters percentage commissions based on the number of sales their links generate. Their other program, 'BFIT', can track and manage click-through, impression and commission-based programs. No pricing information is available at their website, which means that they most probably take a percentage of sales generated from each program.

Central Ad have produced three versions of their ad rotation, management and reporting software. The first, Central Ad 3.0 is free (shareware - $30 registration), and is equipped with the necessary tools to manage and report banner impressions and click-throughs. Central Ad Lite 2.0, priced at $80, also has the ability to rotate ads. Central Ad Pro 3.0J, priced at $159, is equipped with the above-mentioned facilities, as well as the ability to rotate specified groups of banners on certain pages and an automatic removal of banner whose set impression, click-through or time limits have been reached.

DoubleClick is renowned as one of the Web's leading advertising brokers. For sites who wish to take control of their own advertising sales, DoubleClick is offering licenses to their DART software. DART has been rated the #1 ad serving package by Forrester Research due to its unequalled ability to target ads to specific audiences. Obviously, DART can also track, monitor and manage both small and large-scale advertising campaigns.

Facilitate Systems has developed a managed ad delivery product that is specifically tailored to the Australian and New Zealand publishing markets. The system includes post-click tracking mechanisms, and tracks users via a unique Signature Identification process rather than adhering to the controversial cookie standard.

FastClick AdServer is a remotely-hosted ad management solution that offers all the advanced targeting and reporting features familiar to members of FastClick's ad network. This comes at vastly cheaper rates than competitors' similar offerings, with the cost of the service ranging from $0.09-$0.25CPM + graphic bandwidth fees.

Groundbreak.com sells a variety of professional-quality CGI scripts, with its trademark creations being the Ultimate Affiliate, Ultimate Advertiser and AdServer MySQL ad management systems. These are available at comparitively affordable rates, and are amongst the most popular entry-level packages of their type.

i-Depth's Advertising Banner program delivers and monitors banners, providing details of each banner's click-through performance. For the service, i-Depth charge $10 per month for up to 30,000 banner hits (each time a banner is served), with an additional $3 monthly charge for each subsequent 10,000 hits. No programming is required on your behalf, since the code and banners are served from i-Depth's server.

MeySoft Banner Exchange has three products (or versions) of their ad serving software on offer. The first, costing $99, can track and manage banner unpaid banner trade programs, noting click-through ratios and impressions. The second, version 2.3A, is priced at $299. It is equipped with the ability to deliver and monitor 'paid', 'click' and 'sponsor' ads. Version 2.5A, priced at $599, has the added ability to target, block and rotate ads. Their site's unprofessional facade leads me to recommend that you demo the programs (demos are freely available at the site) first before making any financial commitment of this magnitude.

My Affiliate Program presents web marketers with a powerful system designed to manage your own affiliate program. Best known for its strength in tracking and reporting lead and sale-based transactions, this package offers strength and flexibility at an entry-level rate of less than $500.
UPDATE (July 28th, 2005): This system has been repositioned as a solution for larger businesses and enterprise applications. It is now priced at $2000/month.

Radiation AMS has developed a comprehensive ad management utility that provides detailed statistical tracking of a limitless number of banners, blocking and targetting functions and a client log-in facility that enables clients to monitor their campaign's performance. Priced at $1600 (including upgrades and support), the program is not aimed at small-scale sites. Webmasters of smaller sites should consider AMS Lite (see above) as an option.

Open AdStream is an incredibly scalable and flexible outsourced ad management platform developed by Real Media. The system license may be purchased and managed in-house, if you have the hardware and support systems available, or hosted and serviced by Real Media via the Open AdStream Central option. Prices vary according to the service plan and your network's specific requirements.

Ransom's CGI Scripts offer two distinct CGI-based banner serving apparati. The first, which costs $99.95, serves banners on remote sites, while collecting data regarding the number of impressions and click-throughs generated. The second adds an automatic rotation facility, while also providing accurate stats. It costs $40.

WebAdverts has been around since the beginning of time (in internet years), and continues to perform well as a budget solution suited to smaller sites and banner exchange networks. The software is not particularly efficient, though, and can quickly hog up system resources when strained under the weight of a 20,000+ calls/day, so you should have a migration plan in mind as your site grows.