Topoi

I was an early Mapstr user—I liked it way more than Google Maps bookmarking. Tags, collections, profile sharing, all of it. But it recently went paid, and not cheap, so I built Topoi (from the Greek "places"), a full-stack web and mobile app very similar to Mapstr, but free. It doesn't have the network and users of Mapstr, of course (it's mostly for me and my friends), but it does exactly what I wanted it to do.

If you want to try it, you should be able to access it here.