Bored - What do you do?

So I've been talking about how boring math is on my twitter lately, but now a new subject has come to my table and this one is even more boring! We're basicly learning a whole lot of elementary stuff that we've heard before. Without going into further describtion of the subject - I'm going to talk about a little fun way I use to get past this boredom.

About 5-10 years ago I played a game called Transport Tycoon. It recently got to my attention again when I noticed someone playing it during a lesson. Appearently there's a new and free version of it out there called "Open TTD". I use a lot of time to play this game, combine the transportation methods, crash some planes and loose 7 million dollars on that and what not. It's really fun once you get into it!

But now I'd like to ask you, what would/do you use to kill time during small boring lessons of no importance? ;)