Rob Goodspeed brings us WMATA's least-used Metro stations. I go by the Waterfront-SEU station all the time because Sara lives across the street. The problem of underuse there is presumably influenced by the fact that the directly adjacent Waterfront Mall has been closed for a while and is currently a giant pile of rubble. In general, land use in that area has been deplorable (quintessential isolated "towers in the park" urban renewal gone wrong) but things are in the works to improve matters.
Mostly, though, I think this highlights the fact that though nobody wants to confront the construction costs it would really make a lot of sense to build some additional heavy rail tunnels through the center of the city rather than more Metro "spur" extensions. New tunnels and stations through the core would relieve crowding at the very crowded existing central city stations, and would also increase the usefulness of the currently under-utilized stations on the fringe. Yes, obviously, it's more expensive to build downtown, but it makes more sense to undertake expensive projects that meet real needs rather than to go in for cheaper projects that aren't useful.