I'd thought about adding films to rvw for a while but never got round to it - now there's no need, because Criticker has arrived. With an excellent interface (ignoring a few niggles like the inability to go back to a previous page without it changing) and a wonderful sense of discovery, Criticker takes your movie reviews, compares them to other users and professional film critics and recommends both movies and reviewers that it thinks you will like.
The calculations seem to be well thought out, the level of serendipity is good and there's an option to receive weekly emails with updates and recommendations. The only problem I can see so far is a bit of depth lacking in the catalogue, especially for older films (though they're very quick to respond to requests for additions).