One of my favorite songs right now is "Stronger" by Kelly Clarkson. It can pump you up no matter what's going on (although I hate that horrendous Toyota commercial with it).  Last week in spinning class the isntructor played it as the last song for our sprints, boy did I really rock it out and pedal hard! Kelly had a year or so when she wasn't bring us her rocking pop songs, but it seems she's back.  Hopefully she's got more of where this came from.