If you're looking to explore the trails along the Anacostia and/or its tributaries, the Anacostia Watershed Restoration Partnership has a great interactive map of them. Not only does it have Maryland's Anacostia Tributory Trail System and DC's Anacostia Riverwalk Trails on it, but also the Watts Branch, Rachel Carson Greenway, Wheaton Regional Park and Lake Artemesia Trails. On top of that, it also shows the location of all Capital bikeshare stations.
But the real value comes from clicking on the trails at any spot. Then you'll be given a "streetview" image of the trail at that location, with a strip at the botttom showing the terrain of the trail with the selected location marked on it, and a map and compass at the top.