I just wen through a breakup, so a lot of breakup-themed stuff. My current most played tracks are:
Payphone by Maroon 5
Maps (and lots of their other stuff) by the Yeah Yeah Yeahs (late to the party, but they're very good...and the frontwoman is a hottie)
Paper Wings by Rise Against ("I can't tell if you're laughing / Between each smile there's a tear in your eye / There's a train leaving town in an hour / It's not waiting for you, and neither am I")
So Much for My Happy Ending by Avril Livigne (yeah, yeah...make your fun)