Here are some posts from Music of the Spheres on space prizes:
Awesome SpaceShipOne Documentary - This post pointed me to a Discovery Channel DVD on the X PRIZE flights. I have since purchased and watched it. It's worth seeing if you haven't already and you're interested in personal spaceflight, which I assume you are if you're reading this blog, because a lot of these space prizes I'm posting about are related to personal spaceflight, even though personally I like the robotic spaceships too.
If you check out the first link above, you'll see a number of additional prize-related posts. There may even be new ones added after I made this post. Some other posts in addition to the DVD recommentation include one on Virgin Galactic, several on Anousheh Ansari and her space flight, and one on the 2006 Space Elevator Games that were then upcoming.