Some are not related to political elections. Others are hopelessly out of date:
Save the Whales
Send Dubya back to Crawford
Re-elect Al Gore
I was anti-Obama before it was cool
Vote for Monica Lewinsky's boyfreind's wife
Keep the Change
Personally, I don't do bumper stickers. However, if I could find one that says, "Help stamp our Bumper Stickers" I'd buy it on the spot.