This page links to various articles on triathlon, marathon, and ultra running training. In general I have a low-mileage, low-injury philosophy on training, due mostly to the fact that I hold a full-time job and I believe in balancing training with other aspects of life.
Here's a progress report on Dan's goal to run a marathon in all 50 states. I've run about 20 marathons, but they have been mainly in Florida and Texas.
Which Sport Is the Hardest?
See Dr. Kenneth Cooper's (father of Aerobics) scientific comparison of the three sports.