Mike Arrington has covered two really interesting edge players recently - iNods and KritX. He writes:
iNods aggregates blog and other edge review content and displays it in a centralized way for users. Unlike similar services kritX and blogcritics, which aggregate general review information contained on blogs (and are excellent), iNods is completely focused on shopping...Like the others, iNods has realized that there is a massive amount of review information out there in the blogosphere. And more is being created every day. They are harvesting that information, making it searchable, and driving highly targeted traffic right back to the blogs to read that content.
Mike goes on to explain that centralized review sites will lose out to those aggregating decentralized content. This is the same issue I spoke about in my review of Yelp:
[Yelp is] a nice site, but I feel like they've got the same problem as Riffs - there are already hundreds of reviews out there in the blogosphere, and yet Yelp is asking people to create content specifically for their service. This is where structured blogging and microformats come in. Back in November 2005 I wrote about how Riffs could aggregate reviews from the blogosphere, and in mid-December I spoke about the opportunities created by structured blogging. In the long term, I think closed services like Yelp and Riffs are going to lose out to services which aggregate and filter reviews from the edges of the network.