In looking through my options for transitioning away from delicious, Favbot is the one that has we genuinely excited.
If it works in the way that it's described and works well, I daresay I'd consider switching even without delicious' impending doom. The analytics are especially interesting for a stats addict like myself.
I'm not convinced about auto tagging services. The reason why tagging is so great is because the taxonomy is in your head not decided by a machine. Tags are literally bookmarks for your brain, if you're not making the tags - they're bookmarks for a machine (which are then hard to browse/cluster content by.)
Why does it say "Signup For Free Now" if I'm not signing up for the service? You should make it "Signup For An Invite" or something. (I just noticed it says next to it about invites, and on the right on the next page - but no one reads that.)
Smart Automatic Bookmarks.