Washington, DC started a bike sharing program in 2008. The success of this program was arguably the start of Washington's move towards becoming a bicycle friendly city. Today, Capital Bikeshare offers a bicyle sharing service, with over 175 stations and more than 1700 bikes. The system works on a membership plus useage fee.
Bike and Roll/Bike the Sites - 2 locations
Big Wheel Bikes - Near Georgetown
Rolling Cycles - Just north of the White House
District Hardware and Bike Shop - Near Washington Circle
More information about bicycling around the DC Metro area, including links and descriptions of the local trails can be found on BikeWashington.org