OT: Best version of "In the Hall of the Mountain King"
WARNING: Back away now if you don't want the tune stuck in your head:
Op. 46. Conductor: Herbert von Karajan
Op. 23: Conductor: Per Dreier
Richie Blackmore's Rainbow (with lyrics!)
Trent Reznor and Atticus Ross (Social Network soundtrack)
For the sake of expediency I've only included two recordings of the original work, though admittedly they vary greatly from performance to performance. Feel free to post your own favorite!