I need some software to manage a directory of website owners, who each have web sites where they can sell space to advertisers. Most of the ads are text (e.g. a press release) with links. The software would let each site owner register, list their space available with categories, and handle escrow payment to them once a deal is made. It would also allow people with advertising to place, to search the database of space available, and order via escrow. I would take a small % of the transactions and manage the site. I can't think of the keywords to search for such a thing - is this an "ad network platform"? Any suggestions on products or where to search would be appreciated. Thanks, Peter