I am doing photomapping on open street map, which is a great site. It's like wikipedia for maps. Google maps or other services have more detail in some areas, but in the long term nothing can beat open. Plus, you are allowed to freely do things with the data - easily make certain views. http://wiki.openstreetmap.org/
Their philosophy of adding places is really open - you can add anything which can be verified on the ground. That lets it expand in really interesting ways in the future:
I get the feeling that OSM is mostly made up of the type of people I like - ones who get satisfaction from completing and organizing things, and having a nice overview of data. They probably will tend to be good at visualization, too.
I've used iD and JOSM. iD is the default, and is really easy to use, and is pretty great. Plus you can clone it from git and run it locally really easily. JOSM seems much more powerful (once you fight with Java for a while (a minute to an hour).
It is fun to have an open-ended mapping quest.