Here's a great tutorial on making custom maps on Google Maps. Map making could be a great addition to a research project. Could students map out a fictional character's neighborhood or journey? What about a map for a biography book report? Students could add facts about their person in the description boxes.
History students could map battles, migrations, explorations, etc. Even science classes can create custom maps--a map showing active volcanoes, or earthquake faults in earth science, or one detailing endangered species showing original habitat and current habitat.
There are many other features to using custom maps, including adding zones. I've included a shot of one I made when my daughter went to college in South Korea a few years ago.
I'm sure you can think of several applications for making custom maps in your classroom. I'd love to do a contest for mapmaking for fictional books in the library!