HookupMaps is a mix of Craigslist personal ads and Google Maps - showing you where the people wanting to "hook up" in your city are. I wonder if it pulls from the sexually scarey "random encounters" section, "the LTR section" or some other section. It will not only tell you how many single people there are in your neighborhood, but it will also tell you the age and gender of each poster.
The site also lets you filter your searches based on a few criteria: m4m, m4w, w4w, w4m, and whether the post contains a picture. You can search by city, neighborhood, or, by keyword. Here in DC maybe that means you can search for "liberal" or "democrat" or "lawyer" if that's your preference.
There's a different twist on staving off movie watching loneliness that I discovered while at Pop!Tech. It's a blog called "White Hat Stories", where a poster announces that they will be wearing a white hat and watching a movie at X movie theater in case anyone wants to join them for company.
It's interesting to see how people are using technology to encourage face-to-face interactions - like joining groups on Facebook or Meetup.com