Hop on the Duchess Gambit and travel to the isle of Point Lookout, the place the world left behind. The newest DLC from Bethesda for Fallout 3 is now available for 800 MS points, for $9.99, or as part of the double-pack on disc with Broken Steel in August.
Point Lookout is dark, foggy, and full of cabins and swamps. You can leave and return to the island at any point using the ferry, so you can do whatever you like in the captial wasteland, but your allies cannot follow. New weapons include the Winchester Widomaker, a double barrelled shotgun for killing country folk. Yeeehaaaw!