I've been a Dean Karnazes (www.ultramarathonman.com) fan for a while. His ultrarunning accomplishments are incredible. Nevermind his Badwater 2004 (www.badwater.com) and 10 x Western States 100 (www.ws100.com) victories, the guy just keeps running and running and running.
Dean's most recent challenge - currently underway - is the North Face Endurance 50 (www.endurance50.com). What is it you ask? It's 50 marathons in 50 US states in 50 consecutive days. That's a total of 2110km! He started on 16 September and so today, Tuesday 26 Sept is Day 10.
Some of the marathons are actual events. For others - especially during the week - he runs an established marathon route in that State. Dean will end with the New York Marathon in November.
From the Endurance 50 website, follow the link for the Timex website. His speed, HR, calorie expenditure and other such interesting stats are available for each marathon.
Also visit Chris Carmichael's website at www.trainright.com. Chris - Lance Armstrong's coach - is also Dean's coach and advisor (along with others).
On the event website it said something about Dean running 4:30 - 5:00 marathon times. Looking at his first 9 races he's running 3:50 - 4:30 times. Impressive.