I've accepted an invitation to adopt Mendeley desktop and online bibliographic reference management applications, whose features Mendeley Research Networks summarize here. They work with Linux, Mac OSX, and Windows, as well as online, so you can use Mendeley just about anywhere. It was quick and easy to sign-up, and start a profile.
The Import to Mendeley bookmarklet, found through a dismiss-able feature link in the profile sidebar, dragged and dropped sweetly into a biblio. folder in my Xmarks synchronized Firefox Bookmarks toolbar. The CiteULike Importer (Account Settings) set up was almost as dreamy.
I wonder how long it takes to get CiteULike references flowing [in-]to Mendeley, and how seamless sharing references with collaborators will be.
Addenda: Although adding spot-on articles highlighted by Mendeley at login was a piece of cake (shown first by field, perhaps filtered through new research interests), I've found no trace of previous CiteULike citations coming through to Mendeley over the past hour or so. I checked to make sure the CiteULike Importer connection was hot. Anyone know a way to release the backlog?