Yep... Matter-of-fact, there is a guy (Stu Mittleman) who ran 1,000 miles in under 12 days!!!
He currently holds the US record for The Six Day Run: 578 miles (96 miles a day!)
And, on June 6, 1982 he ran 100 miles in 12 hrs 56 mins 34 secs -- That is 7.7 MPH for 13 hours straight!!!!
-Rip