I just ran across this article form the smithsonian with some great info on some of the Extreme bike and foot races thruought the world. This areicle breifly mentions the Race Across america (RAAM), the Badwater ultramarathon, Paris-Brest-Paris Ultracycling event, and even one called the CROCODILE TROPHY. check out the blog article on the Smithsonian site at:

http://blogs.smithsonianmag.com/adventure/2012/05/grueling-travel-through-beautiful-places-the-madness-of-extreme-races/