Don't get me started on great covers.
Too late, you've got me started. I actually have a 12-song playlist (that being my standard template) of my favourite covers. They are thusly:
SikTh - Tupelo (Nick Cave)
Editors - Orange Crush (REM)
Happy Mondays - The Boys Are Back In Town (Thin Lizzy)
Warren Suicide - Yer Blues (The Beatles)
Guns 'n' Roses - Live And Let Die (Paul McCartney, possibly with Wings?)
Lostprophets - Cry Me A River (Justin Timberlake)
Metallica - Tuesday's Gone (Dire Straits possibly?)
Radiohead - Be Quiet And Drive (Deftones)
Nick Cave - Disco 2000 (Pulp)
Johnny Cash - In My Life (The Beatles)
The Beatles - Twist and Shout (I don't know the originator, but I know the Isley brothers did a version)
Rage Against The Machine - Maggie's Farm (Bob Dylan)