On The Macintosh Biblioblog, Joe Weaks has an interesting post called CiteULike for web-based bibliography citation. Here's the link:
I've played with it a bit and it works fine for me when added Amazon books to a bibliography, but I can't get it to work properly with Ingenta articles, though it is supposed to. Might need to play with it some more. It looks like it is fun and helpful if one could get on top of it.