Raw

revyu.com is a web site where you can review and rate things. unlike other reviewing sites on the web, revyu.com lets you review and rate absolutely anything you can name.

Has familiar Web 2.0 features such as tags, bookmarklets and pastel colours. Adds Semantic Web capabilities such as (eminently mashable) RDF representations of entries and a SPARQL query endpoint : "use reviews from revyu.com on your site", but really needs more docs on how. But there's a load more stuff on their to-do list (I made a few requests myself) and it is declared as alpha alpha alpha... Does seem to work nicely. It's built on RAP - the RDF API for PHP, mostly using Review, FOAF, Tag vocabularies. There's also a short paper (pdf) from ISWC 2006.