For Uppers: Eye of the Tiger by Survivor Wonderwall by Oasis Don't Stop Me Now (Mr. Farenheight) by Queen and Homeward Bound by Simon and Garfunkel
For Downers: Leader of the Band by Dan Fogelberg Dance with My Father by Luther Vandross and the saddest song ever is the country song about the boy who wants to buy Christmas shoes for his dead mom.
A song that always picks me up and I always end up singing along with is "No Rain" by Blind Melon. Another song that always has an affect on me is "November Rain" by Guns N Roses. Ah, to be a young, depressed college student again.
This is actually one of my most thought about questions. When you think, do you "hear" an internal monologue like in a movie/tv show? For me, it only happens when I'm writing something, to make sure the dialogue sounds natural.