About 10 years ago, I taught myself web programming by writing <a href="https://dirtywalls.com" rel="nofollow">https://dirtywalls.com</a> which is still up and which occasionally I still see used by a handful of the folks I shared it with back then. Same basic idea: pseudonymous message boards attached to real-world locations, where you must be within a certain proximity to read or post.<p>The concept at the time was "4chan meets foursquare." and the inspiration was rediscovering some graffiti in a bar bathroom that years before had particularly tickled some friends and I. For awhile, I added new locations as I traveled extensively for work, so there are hidden little message boards around NYC, SF, China, Seattle, Europe...