I find posting or writing down (basically expressing) what I'm feeling, what's bothering me.. helps a bit. Otherwise the thoughts just tend to go over and over in my head, which does nothing but worsen my mood.
Other than that, I try to do other things to take my mind off things. Browse sites with funny content, watch something funny on TV. Anything that'll get a laugh out of me.. if only temporary. Oh, and cooking, esp. baking is something else that I like to do. I like to see if I can make anything edible with just a few ingredients, heh.