Forkers Central

At least in the cover song category, this has to be in the top five:

Final Countdown

Dammit. Websense is blocking that site here at work. I'll have to check it out this evening.

As for worst of all time, I'd have to nominate Crazytown's "Butterfly." That song made me want to open up a vein or two.

once he started singing my head exploded