Graffit Map lets you choose a Google Street View from anywhere in the world, draw graffiti on it, and then save and share the image.
I think it could have been a useful tool for students studying geography or planning a field trip so they could label things, and it could also be helpful to English Language Learners for learning new vocabulary (sort of like a freehand “Thinglink” that doesn’t require registration. I say “could have been” because the brush size is too thick and unwieldy for labeling use — at least, it was for me. If you can figure out a way to make it more usable, please let me know.
Thanks to Google Maps Mania for the tip.