CouchDB's support for "views" and using comet/websockets (have they implemented websockets yet?) to communicate with a JS app served from the DB itself... Riak

CouchDB's support for "views" and using comet/websockets (have they implemented websockets yet?) to communicate with a JS app served from the DB itself... Riak does too - any DB that implements a RESTful interface to the database instead of a binary protocol. CouchDB is particularly well-suited for this use-case though (I would never use Riak in that fashion).