A couple of my friends are involved with BNI - Business Network International.
It's a nationwide group of professionals who regularly meet to discuss business, support each other, and offer referrals for business.
I've been considering joining the group, and the only thing holding me back is the timing of the weekly meetings. But, I was happy to say "Heck, yeah!" when they asked if I wanted to show off our photobooth at a mixer they were hosting. We rarely do free events, but this one seemed like a great opportunity to drum up some new business leads. Plus, it was local, on a Monday evening when we weren't booked, and we had nothing else to do :)
I ended up meeting a lot of folks from many different areas of business. It was interesting to talk to them and brainstorm on-the-fly with them about how we could use a photobooth to promote their business.