Bub

Welcome to the Jungle by Guns N' Roses
Smoke on the Water by Deep Purple (most influential riff of all time)
Man in the Box by Alice in Chains
Smells Like Teen Spirit by Nirvana
More Than a Feeling by Boston
Enter Sandman by Metallica
Raining Blood by Slayer
One by Metallica
Whole Lotta Love by Led Zeppelin
Kashmir by Led Zeppelin
Black Dog by Led Zeppelin
Stairway to Heaven by Led Zeppelin
Grind by Alice in Chains
Creep by Radiohead
My Iron Lung by Radiohead (a really cool eerie riff)
Paradise City by Guns N' Roses
Ride the Lightning by Metallica
In Bloom by Nirvana
Breed by Nirvana
Lithium by Nirvana
Woman by Wolfmother
Mother by Danzig
Shine by Collective Soul
Sex Type Thing by Stone Temple Pilots
Rusty Cage by Soundgarden
Run to the Hills by Iron Maiden
Breaking the Law by Judas Priest
You've Got Another Thing Comin' by Judas Priest
Give It Away by Red Hot Chili Peppers
Snow ((Hey Oh)) by Red Hot Chili Peppers
Siva by The Smashing Pumpkins
Zero by The Smashing Pumpkins
Cherub Rock by The Smashing Pumpkins
Today by The Smashing Pumpkins
1979 by The Smashing Pumpkins
Californication by Red Hot Chili Peppers
Before I Forget by Slipknot
Wait and Bleed by Slipknot
Walk by Pantera
Cowboys from Hell by Pantera
Ace of Spades by Motörhead
Blind by Korn
Freak on a Leash by Korn
Coming Undone by Korn
Walk This Way by Aerosmith
Dream On by Aerosmith
My Hero by Foo Fighters
Everlong by Foo Fighters
Best of You by Foo Fighters
Alive by Pearl Jam
Even Flow by Pearl Jam
My Generation by Thw Who
Sweet Leaf by Black Sabbath
War Pigs by Black Sabbath
The Beautiful People by Marilyn Manson

Those are just a "few" I could think of.