If I had something to do, I wouldn't be bored in the first place, right?
Anyway, it depends on my situation of boredom.
If I am bored listening to lectures, I would scribble around my notepad or daydream.
If I am bored in public, I normally will take pictures of random stuffs.
... Aw. When I'm bored, I will just blog or pluck out white/black heads. (T3T)