I stumbled across a great website today while searching for non-commercial links to add to some Localism Sponsored Communities.

ShowUp.com

From their "About Us" page:

"ShowUp.com is the resource for what's happening in theaters, museums, and outdoor venues throughout Greater Phoenix. The goal is to supply a comprehensive calendar of events, bringing together into a single convenient online site information that was, previously, scattered or not readily available at all. ShowUp.com lets you click or browse to find performances and exhibitions, classes and workshops, venues and artists. It even provides information about discount tickets (last-minute and otherwise). ShowUp.com tells you what's showing up on stages and at cultural destinations, providing you with date, time, and even maps - so all you have to do is Show Up."

I notice that they are networked with similar sites for cities in Texas, Colorado, Michigan, North Dakota, North Carolina, Tennessee, Virginia, California, Indiana and Utah.  Definitely worth a look!