Educational, and Good Fun Geeky Waste of Time: StackOverflow!
From not-so-news-anymore department: I have grown addicted to another geeky game of sort: StackOverflow.com . It's just a simple question/answer site for programmers, but thanks to its game-like scoring system and merit badges it is subversively addictive. Perhaps I shouldn't be surprised, really, having been addicted to on-line games before: but at this point I should know better. :-)
On plus side (well, additional plus?), usage can actually be useful and educational too. Beyond trying to increase your karma by answering (and commenting, voting) many answers (and questions too) are actually useful and interesting. After all, there are only that many co-located knowledgable co-workers from whom you can learn. But number of colleagues you can collaborate with in virtual environment is less bounded; and in many ways ranking is more merit-based than the pecking order at your one's place of employment. This makes it easier to consider answers more on merits of themselves than on popularity of the guy who answered it (of course you can be a fanboy too and just look at ranking -- there's Jon Skeet that knows everything -- it's up to you)
At any rate: if you happen to roam about, I decided to use another Alter Ego there (StaxMan) -- but you can still see the usual cowboy logo, to spot me.
And now, if you'll excuse me, I am off to earn my first thousand points and a silver badge!