I've been going to house shows for most of my life and the idea of an app scares me. In a lot of places this is illegal and you can catch a ton of heat from the police regarding it. Putting the information out there where it is publicly accessible is a big no-no for a lot of DIY house/basement show promoters. If I ran a house/did shows in a semi-legal space like this I'd cancel any show that somehow got put into an app.