That sounds like a silly idea, but Microsoft might offer soon some cashback to their search engine's users "when they buy things they find through Microsoft's Live Search".
Maybe that will help them regain ground over Google, but the question remains, would you use their search engine more than for the occasional purchase? Not so sure, he he he!
Here's an article that details the project:http://arstechnica.com/news.ars/post/20080521-back-to-the-90s-microsoft-to-bribe-users-to-use-live-search.html
If they go ahead, we might see some nice deals to share on here...