Damn, that sounds like a fun way to pass a day. Too bad some people show no appreciation for such deeds.
I live on a fairly busy bicycle traffic street, just a few blocks away from the Mississippi trail system. I am planing on setting up this room off of my deck as my new bicycle repair room, and hang a sign off of my fence whenever I am in there. Doing the same sort of stuff, free tune up, air, etc. it would probably be a nice way to meet people.