Last year NASA offered you to send your name to the moon on the LRO. The LRO rocket took off successfully on 6/18. But if you missed that ride, NASA now offers you to send your name to Mars on the Mars Science Laboratory Rover.
The rover is scheduled to take off sometime in 2011. My recommendation is to add your geo-location coordinates, so the aliens can locate you more easily (I doubt they use our zip system)