Hoodoo. I listened to it a while ago, thought it was weird, didn't like it. Now I think it's a great song. It's just that the beginning riff isn't very... Muse-y. I didn't think Take a Bow was a very good song either, now I like it.
Also, when I first bought Absolution, I always skipped over Falling Away With You and Blackout, now I love them both.