Blender.com has released their list of the "Wackiest Cover Songs on the Web". There are some pretty awesome ones:

Alanis Morissette, "My Humps"

 

The Polyphonic Spree, “Lithium”

 

Cake, "I Will Survive:

 

The Gourds, "Gin and Juice"

 

Ted Leo, “Since U Been Gone”

 

The Flaming Lips, “Can’t Get You Out of My Head”

 

Nina Gordon, “Straight Outta Compton”

 

Luther Wright & the Wrongs, “Another Brick in the Wall”
(no link available)

 

Richard Thompson, “Oops!… I Did It Again” and Fountains of Wayne, “…Baby One More Time”
(click here)

 

Me First and the Gimme Gimmes, “I Believe I Can Fly”