Unusual songs

I like Travis' cover of "Hit Me Baby One More Time", Smashmouth's "Sorry About Your Penis" (the only song they had that was entertaining - from teh closing credits of Orgasmo), The Greenskeeper's "Lotion" (the Silence of the Lambs track), Brown Bamboo, and the sheer gayness of "Saturday Night's Alright for Fightin'" by Sir Elton.

the whole catalog of the band Ween...they kick ass

You are so right. I need to pick up some of their stuff - my roomie used to have a bunch but he's not my roomie anymore since Amy made me break up with all of my friends.
 
Gray Kid - Paxil Back parody

Though you'd have to be living under a rock not to have heard it.
 
anything from Richard Cheese. Unusual cuz he does the music in ways you woulda never thought.

How about a 20min long song with no breaks/pauses? That unusual?
Meshuggah - I (band - song)
 
I am listening to Daath. They have a song, Death on the Dancefloor. It is a mix between death metal and dance (drum and bass). It is very scary combination that works surprisingly well.