Best covers of popular songs?

In the past I wasn’t really big on listening to cover songs, as I always figured the original song is better (silly, I know). Since listening to Yael Naim’s cover of Britney’s Spear Toxic. I’ve been wondering, what other good cover songs of popular music have I been missing? By popular music, I mean songs that most people know about.

I’m set on making a mix cd full of the best cover music for an upcoming road trip. I’m looking for songs from all genres.

Any suggestions?