Back before I felt comfortable taking my expensive smartphones running with me for the GPS purposes, I'd manually enter my running routes into RunKeeper. I don't know if they still use it, but back then their mapping was powered by OpenStreetMap. I'd add in stuff like sidewalks and trails that weren't on the map yet to make my manual entries easier. I liked doing this--it was kind of fun and I felt good contributing my knowledge of my local unimportant suburb to the world.

I've been surprised at how much is already on there, though. Out of curiosity I went to look at the map for my mom's hometown of ~500 people in the middle of nowhere and found it surprisingly complete.

I still like OpenStreetMap, but don't use it as much anymore. I wish there was a navigation app that used OSM data and was able to give me audio cues (e.g. "turn left at the next exit"), because that's 99% of my map use these days. (And if there is one that I don't know about, please let me know!)