I guess a lot depends on how "easy" is "easy." Louie Louie and Wild Thing come to mind. A lot of U2 lines, like With or Without You (good exercise for keeping steady tone and tempo over a long, repetitive time...) or Desire. Just about anything by AC/DC. Running with the Devil (Van Halen). I Love Rock n Roll. Roadhouse Blues. Mary Jane's Last Dance, definitely. I think the first tune I ever learned was Talking Heads' Take Me to the River.
Someone mentioned Stray Cat Strut - the basic roots are simple, sure. If you're going to do the walking lines on the instrumental breaks, though, that's a whole other ball of wax. But Rock this Town is pretty simple. Someone else mentioned You May Be Right, which I agree isn't HARD to play or anything, but it isn't the kind of simple three-chord wonder you can just jump in on.
Oh that reminds me - most hits with the Bo Diddley beat. I Want Candy, the Hand Jive, etc.