Although this is still a Beta version, I really like Frappr, a service that uses Google maps. One can create a map in which members of a group can leave a pin indicating their location. I helped started one for educational bloggers at http://www.frappr.com/thisweekineducationblogmap and I just joined one for independent school teachers at http://www.frappr.com/ised.
Why create a Frappr map? First of all, it's just interesting to see where people are located. For instance, the ISED one gives a face to people who respond regularly on the Independent School mailing list. Secondly, it's a great way to network. I have already had one teacher contact me from this map as she's relocating to Chicago. In the case of the This Week in Education map, the map provides a source for finding other interesting blogs. I think the potential of this service is enormous.
Today I was happy to find that one can join Frappr and create an account which serves as a central repository for all maps one has subscribed to. I hadn't noticed this feature before, and it looks like there are some others worth exploring. It's now possible to message other Frappr members andto create map pinpoints for other places such as where one works or favorite restaurants etc. Perhaps My Maps has always existed; I just hadn't noticed this until today!