I've just been trying RadiusIM, an instant-messaging service with a difference. The difference? This IM client introduces an element of social networking to instant messaging. And you can see where people are.
RadiusIM is a web-based IM service that allows access to any or all of your MSN messenger, AIM, Yahoo, GoogleTalk or Jabber instant messages, without a desktop client. And once you've registered, you can surf about to find other RadiusIM messengers in your physical vicinity. Or you can sit still, make yourself available to be found and watch the new friends roll in.
The potential for spontaneous meetings with old friends or aggressive marketing to former clients is huge. Almost as big as the marriage-wrecking potential of allowing previously harmless flirting to have a physical outlet.
Perhaps fortunately, all these things will have to wait. As clever as RadiusIM is, UK users seem thin on the ground. When I went a hunting for friends in, er, central London, I was all alone. Is there anybody there…?