As much as I hate Facebook for its annoying apps, there are one or two good ones.
Cities I’ve Visited is one such app that I like. You can add new cities either by scrolling, zooming & clicking, or by typing in a name. I like maps so I find it pretty interesting to see where I’ve been.
The application itself uses the Google Maps API so it’s interactive. Unfortunately the embedded version of this app for blogs is just a static image. You can’t change the zoom level or centre point, which is annoying, since you can see I’ve never been to America or Asia.
One day I might have a go at building my own app for fun. It shouldn’t be horrifically difficult to build a simple, single-user app for having an interactive map with points on it. The difficult parts are making it multi-user, and having a system for adding cities by name (rather than by grid reference).