Let me start by saying I checked out Pandora.com and listened to it daily for about 2 months. I set up nearly 100 stations. I found a new freebie music site on the web about 2 weeks ago that is 10x better than Pandora (IMO) its called Purevolume.com. Its great for discovering new artists, not so great for checking out older more established artists.
OK so here's some new stuff I've been listening to:
Good all-around rock:100100 Juggernaut
Arctic Monkeys
The Classic Crime
Bedlight for Blue Eyes (great lead singer)
Muse (of course)
Jonas sees in Color
The Receiving end of Sirens
Unique/experimental trippy stuff:Sound of Animals Fighting (this band is going to be huge in a "cult" following way...there too bizarre of a sound though to ever have commercial success..maybe in 10 years regular radio will accept them)
Mars Volta
Heavy stuff that is quality metal:Shadows Fall
Still Remains
What I'm sick of:- the 1000's of copycat emo/scream rock/power pop crap thats out there
- the new trendy metal bands that think its hip to switch singing style between the demonic growls and the harmonic sections in every song. Lame, lame lame.
- all of the "smooth operator" John Mayer wanabee singers/acustic guitarists. Stop whispering dudes you ain't gonna pick up chicks being a copycat.
With all that said though I do respect John Mayer and Jack Johnson as songwriters and like their stuff.