Great thread!
Best
I Fought the Law * The Clash
Originally by Sonny Curtis & The Crickets
Romeo & Juliet * The Killers
Originally by Dire Straits
The Man Who Sold the World * Nirvana
Originally by David Bowie
The First Cut is the Deepest * Rod Stewart / Sheryl Crow
Originally by Cat Stevens
Mercy Mercy Me * Julian Casablancas & Eddie Vedder
Originally by Mavin Gaye
Blowin' in the Wind * The Hollies
Originally by Bod Dylan
What a Wonderful World * The Ramones
Originally by Louis Armstrong
Twist & Shout * The Beatles
Originally by Top Notes
Working Class Hero * Green Day
Originally by John Lennon
Hallelujah * Jeff Buckley
Originally by Leonard Cohen
Maybe I'm Amazed * JEM
Originally by Paul McCartney
Mr. Tambourine Man * The Byrds
Originally by Bob Dylan
With a Little Help from my Friends * Joe Cocker
Originally by The Beatles
Babe I'm Gonna Leave You * Led Zeppelin
Originally by Joan Baez
Life's a Gas * The Strokes / The Ramones
Originally by T.Rex
Worst
American Idiot * Avril Lavigne
Originally by Green Day
Take it or Leave it * Arctic Monkeys
Originally by The Strokes
Behind Blue Eyes * Limp Bizkit
Originally by The Who
My Generation * Hillary Duff (??)
Originally by The Who
Seu Jorge singing Michael Jackson. (??)
Guns of Brixton * Nouvelle Vague
Originally by The Clash
Knockin' on Heaven's Door * Avril Lavigne
Originally by Bob Dylan
That's all I remember.