MyLoki is a new website that lets you share your location with your friends via Google Maps. You can change your location at your own MyLoki page or (and this is the clever bit) you can download the Loki toolbar for your browser and update your location automatically.
The Loki toolbar can triangulate your location when you are in range of a WiFi hotspot and update your profile. You can then share your location with your friends in a number of different ways. You can share the address of your own public page. Alternatively, you can embed a map in your blog to show your last recorded location or add a map to your Facebook account.