When I'm angry or depressed, I usually lie on my bed and listen to some relaxing music, like Robbie Williams' "Swing When You're Winning" or any of my movie soundtracks (the Shrek OST and Star Wars is a fave, I also have the Pokemon 3 Ultimate Sountrack which is also great cause the songs are all about love, helping each other and having a good time - the second disc is actually the score for Pokemon 2000, which is very good).
And now that I have Evanescence's debut album, "Fallen", I listen to that all the time. It's rock, but somehow, it's really relaxing. I guaruntee you, when you listen to Amy Lee sing those songs (especially "Hello" - the most beautiful song ever), you go in a trance, forget everything, and just feel good. You also, for some reason, just fall madly in love with her for a while, but that's just me.
So download/buy their album, and listen to it. You willl love it. I'm serious. Although if you're depressed, don't think about the lyrics to 'Tourniquet'. It's a good song, but it's about suicide. Haha.
After all that, I have a VERY long sleep.