"Pluto is For Lovers"
"Pluto: Voted Off the Solar System"
"I'd Rather Be an Asteroid Anyway. No, Really!"
"Sorry, We Just Had to Make it A Nice Even Number of Planets."
"One Word: Planet"
Off Topic: Everyone go see Beerfest! I saw it this weekend and it was AWESOME!
I like the "Independent Planet" bumper sticker.