I host the Light Rail Relay in Seattle, an event where people run the length of the 1 Line. Over the years I've built a web map that includes an annotated on-foot route as well as live transit info. OSM Data, self-hosted PMTiles in MapLibre + One Bus Away API used from the client side to draw trains and arrivals.

The registration and results system (Pantograph, see links on page) are also homegrown. If you or your coworkers are looking for something fun to do together this weekend, come run (or walk) and try things out!