Wolfmother - it's like Led Zeppelin, Black Sabbath, The White Stripes all fused into one band! These guys rock, and are one of my favourite bands! Try "Joker & the Thief" or "Love Train".
Arctic Monkeys - probably the leaders of the current Indie rock scene over in England, and they're fucking cool, man! Try "I Bet You Look Good on the Dancefloor" or "Flourescent Adolescent".
Dream Theater - a Progressive Metal band who never fail to amaze me with their virtuosity. Try "Pull Me Under" or "Take the Time".
The Fratellis - another British Indie band. Check out "Chealsea Dagger" or "Creeping Up the Backstairs".
Muse - Possibly the greatest modern Rock band? Try "Knights of Cydonia" or "Invincible".
My Chemical Romance - They're actually a really good band, BEFORE The Black Parade. Anything on The Black Parade is a bad example of their music. Try "Demolition Lovers" or "Vampires Will Never Hurt You".