Depends on if you mean all time/career or single season
In 1992, Barry Foster set the Steelers single season rushing record with 1,690 yards.
Michael Vick rushed for 1039 yards in the 2006 season to set the single season rushing record for quarterbacks.
Through the 2008 season, that is Edgerrin James with 1,709 rushing yards in the 2000 season.
Eric Dickerson - 2,105 yards
As of the 2007 season, the Eagles single season rushing yardage record holder is Wilbert Montgomery who ran for 1,512 yards in 1979.
Tim Tebow with 20 in 2007.