Here's a list of cool (and easy) riffs that I know. I usually end up playing most of these at some point during a practice session.

Enter Sandman
Pretty Woman
Cat Scratch Fever
Day Tripper
Fade To Black
James Bond Theme
Black Dog

Anyone got some other cools riffs to add?
Quote by Andrew C. S.

Oh hell ya.. anything tool
I guess SOAD would also be a good one if you dont hate dropping E

Also im getting into Black Stone Cherry... They make textbook scales sound pretty sweet and fun to play
neil young- my my hey hey has a pretty cool riff actually
When they kick at your front door
how are you gonna come
with your hands on your head
or on the trigger of your gun
Ac Dc Have some pretty cool riffs:p but i guess you all know that:>
Kiss: Deuce (Cool riff that can be played by beginners)
Quote by NoSmokingArea
Soundgarden riffs from Badmotorfinger, (jesuschrist pose) (rusty cage) (drawing flies)

Yeah, that's a great album, the riff in Somewhere is probably my favorite off of that album.
Oct. 20th, 2009: New guitar AND front row for Mars Volta.

Quote by denizenz
Is that a ukulele in your pants, or did you just rip ass to the tune of "Aloha Oi"?

I met Sonic Youth on June 30th, and Mars Volta on Oct 20th.