Could work for singles too. Instead of a dating site that matches people to each other, it matches people to fun activities and events. Send a bunch of singles or couples to Cocktail-making or salsa dancing class and they've got a common ground to talk about and can still enjoy even if they don't find someone.
though part of what i like about it is the idea of two people using a computer together. the internet is so bizarre in that it connects you to others who are far away, but simultaneously isolates you from folks who are nearby.
you'd have a shared profile, which is matched with other local couples with similar tastes in movies, music, food, whatever.