"Jellyfish, TheFind and MyTriggers ... are taking advantage of what some executives say is increasing discomfort with the pay-per-click model, which has grown more expensive as marketers bid more aggressively for premium space alongside search results. On these new sites, advertisers typically pay only when someone actually buys something or when users view an ad, as will soon be the case with TheFind."
Instead of cost-per-click, these new shopping comparison sites charge per conversion. Jellyfish, in particular, is doing something very cool: merchants bid for placement for specific products (like iPods or snowshoes), and a significant part of their bid is credited to the shopper as a discount on the item they purchase. It's a good deal for merchants because they can control exactly what their conversion costs are, and it's a great deal for shoppers because they save a little extra cash.