Radio

[Wisemon]

To expand upon my point, I should also mention some of my favorite bands that I was only able to hear for the first time by not listening to the radio:
Rise Against (before they made it to the radio)
Good Riddance
Less Than Jake (before they made it to the radio)
Soul Asylum (the punk albums they put out in the 80's)
Husker Du
Hot Water Music
Bad Religion (surprisingly, they haven't made it to the radio since switching back to their own label)
Kicked in the Head
Minor Threat
Split Fifty
Zero Down
Only Crime
American Lesion
The Draft

Now, to be fair, I should also mention the radio bands whose albums I've been proud to buy:
A.F.I.
Audioslave
Foo Fighters
Metallica
Puddle of Mudd
Rage Against the Machine
Shinedown
Silverchair
Soul Asylum
Soundgarden
Stabbing Westward
Stone Temple Pilots
The Offspring
"Weird Al" Yankovic

I guess what I'm saying is: The radio is a good place to start to figure out your tastes, but it's not where you should end up.