How do I deal with stress? Music.
The last big presentation I had to do last semester, I was worked up. (Last-minute small stuff, really. Moral of the story? Get it done five weeks in advance to practice.)
So I went in search of some music to calm me down. I downloaded
John Cena's "The Time Is Now" (iTMS link) on a lark (and partially because my roommate watches WWE RAW and his entrance music was stuck in my head), and loaded it on the iPod. Worked like a charm. Don't even know why it worked...but I figured I'd share.
(Since that's only three minutes, and I needed a bit more music, I wound up sticking it in with a playlist of other songs, including some Wu-Tang Clan, Incubus, OutKast, and Chocolate Starfish-era Limp Bizkit. Fill yours with whatever gets you mentally ready.)