Below is a youtube video series on Project Orion. I have yet to watch all of the videos.
The best part of Project Orion is the fact that it could, with proven technology and reasonably small costs, send people to Mars and beyond in style. Indeed manned missions to Saturn and Jupiter could also have been done. A small Orion spacecraft could even be launched into near space with solid rocket motors, and then turned on at a safe altitude. This would be a great use for the large nuclear stockpiles in the US and Russia. Source