I've been using a fantastic service for a number of months now and I notice that it hasn't been discussed so far at this forum.
It is a traffic generating service kind of like ping.fm but with some really unique features.
I first read about it on Tim Ferriss' blog here:
Exclusive First Look: SU.PR – Stumble Upon’s New Traffic Builder
I highly recommend
Su.pr - Drive More Traffic with Your Short URLs! for anyone who would like to be able to auto-update your social profiles with your latest content in one simple process.
It also gets you connected with StumbleUpon which has been discussed at length in another thread.
Enjoy