Implement advertising by way of API or Web Service(repost)

We have invented a new plug-in for a variety of browsers which you can see in this 60 second demonstration: [login to view URL] This plug-in sends the users search string back to our site to obtain a relevant ad to show beneath the (+/-) buttons. We would like to set it up to obtain a relevant ad directly from some reputable online advertising company which allows this through an API or web service. The div that has the (+/-) buttons in it is coming from an asp.net page with a C# code behind. You can solve this problem with either javascript or C#, whichever you think would be most effective. We would also appreciate any advice you may have as to which advertising service is the best for this purpose. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform This needs to run from an ASP.Net web site with C# or javascript.