Startup Idea : Open Mic nights

I'd like to see an app/website where musicians could find places to turn up and play within a defined radius of any location. Musicians and venues are useless at maintaining lists of open mic nights, so this would have to be community-maintained. It would invite reviews and be easy to join and update collectively. E.g. I see a regular open mic night on Tuesdays at 8pm at venue 'x'. I turn up and find out next week they're putting on a tribute band instead, so I quickly add a note to the 'calendar'. I don't want to see to 'The Beatalls' or 'Bled Zeppelin', so I send out a message asking if anyone knows another open mic on Tuesdays, or a suitable venue where we could persuade them to host one. Over time, the regular events accumulate and there's a one-stop source of info about where I can play on any given night in any location.