Last fall, I went to Startup Weekend here in Columbus, courtesy of the NEWPATH technical entrepreneurship group here on campus. It was a lot of hustle and a lot of fun.
Freeloader, the project we built that weekend, is a freebie spotting app. When you find a freebie, you post it to the app with an address and a description. The app can give you a list of freebies in your area ordered by distance, and will send you push notifications for new freebies posted nearby. It's not on the app store yet, unfortunately.
If you're not familiar with how it works, on Friday night there's an introduction and then everyone pitches ideas (some more than once). I had a rough outline of an idea before I showed up, and I fleshed it out in my mind as the evening went on. I pitched it that evening - something like
Hi, I'm Jeff Casavant, and I want to find the free food. After the pitches, there's voting, and the top fifteen ideas are brought up to the front. Freeloader wasn't in the top fifteen, but I formed a team around it anyway.
Folks I worked with - go ahead and contact me if I don't have you and you worked on my team:
We accomplished quite a bit over the course of the weekend: we got a functioning Android app and some good business hustle. We haven't done anything more with it since then, but it's a viable idea.
Edit 2015-03-12: Something similar has existed since 2011.