looking for PPC software like phpadsnew

I'd appreciate your suggestions on some software that will do the job here:

I've got a search engine type site that I want to serve ads on, depending upon what was searched for. I'd like advertisers to be able to sign up for their own accounts, deposit money, choose keywords and develop ads; then have the system automatically serve those ads.

Basically, what Google and Overture are doing .

Doesn't have to be free software though I would prefer to not have a hosted solution - I'd like the software to run on our own server. Even better if I get the code so we can tweak it as needed.

phpadsnew would have been nice, but doesn't quite have the autonomy we need for account creation and setup.

 

there's this thing called revsense (http://www.w3matter.com/products/adrevenue), although i did not like it at all and would not recommend it to anyone.

i found two other ones over at hotscripts.com before, but i cant seem to find them now. i remember that one was horrendous and the other had a revenue model that took x% of your ad revenue, which made it not even worth considering for me.

i been looking for a clean-coded open source software like this for some time, but havent found any luck.