I have to admit an addiction to Facebook. Not so much for the making of friends - although it's very nicely re-introduced me to a couple of old University friends I'd thought long in my past. No the thing I like (and dislike) about it is that it has puzzle games likes Scramble, Word Twist and Pathwords - all of which allow you to play against friends.
And there's nothing I like more than word games.
The result - I've spent another lunchtime playing games on Facebook when I really intended to do some research for a history article. Darn! Good fun though.