Texsy depends on APIs from Amazon, Ebay and Shopping.com to show products. And the publisher makes money when someone buys a product or (in the case of shopping.com) clicks on the ad.
The biggest problem I've had so far is that hardly any one who signs up for Texsy has a Shopping.com affiliate account.
Right now is a great time to have a Shopping.com account, because their payouts are 30% higher in Q4 than they are the rest of the year. Holiday shopping drives a ton of traffic and CPCs go up.
SO - go get a shopping.com partner account, and try Texsy for your forum, blog, wiki, or product site!