As John Kerry proved in 2004 you can have all the A-list celebrities endorse you and it doesn't mean a a key to the White House. So I've done a little research (ok, so I just looked it up on Wikipedia) and I've found a few interesting celebs endorseing 2008 presedential conidates. Will this help you decide?
The Dems
For Barack Obama: Jesse Jackson, Ken Burns, Chris Rock, Will Smith, Usher, Oprah Winfrey, Kal Penn, Olivia Wilde, Brandon Routh, Brad Pitt, Ben Affleck, George Clooney, Halle Berry, Scarlett Johansson
For Hillary Clinton: Candice Bergen, Chevy Chase, Michael Douglas, Bob Vila, Barry Manilow, Madonna, Janet Jackson, Melissa Etheridge, Barbra Streisand, Martha Stewart, John Grisham, Rosie O’Donnell, Jerry Springer, Hugh Hefner, Berry Gordy, Magic Johnson, Maya Angelou, Jenna Jameson, 50 Cent, Steven Spielberg
For John Edwards (my personal endorsement): Kevin Bacon, Tim Robbins, Madeleine Stowe, Harry Belafonte, Ralph Nader John Mellencamp
The GOP
For Rudy Giuliani: Adam Sandler, Kelsey Grammer, Kevin James, John Elway, Pat Robertson, Jeff Gordon, Donald Trump
For Mike Huckabee: Chuck Norris
For John Mccain: Kurt Schilling
For Ron Paul: Krist Novoselic, Joe Rogan, Howard Stern