Here you can click on a link and listen to whole songs. The quality isn't as good as a CD, in fact it isn't too great at all, but never the less, it's still worth a listen. Most are in RealAudio format, so you probably should have that to listen to them. If you don't have it, get it here. Here are some of the better bands out there:
Love Core (Welcome To)
Turning Inward
Hidden Track On Time Bomb
Porno Star
The 18 Second Song
America
Gone
In My Head
Letting Go
Paper
Puzzle
Rock Superstar
Back To School
The Chauffer
Winter Kiss
Killing The Me In Me
Cheese Wheel
Insane In The Brain
Screaming Jesus
Full Devil Jacket
Where Did You Go?
Hangman
IFO
Crazy Legs
The Meadow
Jesus (of Nazareth)
Bump (Hardcore Remix)
High Society
Peace Not Greed
Wickit Klowns
Breakstuff
Nookie
Hot Dog
Hold On
Nobody Loves Me
Stalemate
Stink Finger
Fade To Black
For Whom The Bell Tolls
Welcome Home (Sanitarium)
One
Nothing Else Matters
King Nothing
The Unforgiven II
So What?
-Human
Dig
Internal Primates Forever
Seed
Poop Loser
Severed
So Fresh, So Clean
Gasoline Dreams
New Millenium Homes
The Ghost of Tom Joad
F*ck tha Police
Darkness
People of the Sun
Bulls on Parade
Vietnow
Bombtrack
Killing in the Name
Bullet in the Head
Know Your Enemy
Freedom
Happy
So Far Away
On Your Way Down
Safe Place
Me
Excess Baggage
It's Been Awhile
Outside