1. Make (or gather) stuff that's edible and swappable, i.e., a loaf of bread, a jar of preserves, a half-dozen eggs from your backyard chickens, portions of soup, packages of homemade candy, etc.
2. Find a friend or two who can share the planning and hosting duties. It's about the same amount of work as hosting a potluck every month or two (and in other-location cases you won't even need to clean your house).
My friend Meg and I formed a team; we called ourselves BK Swappers. Create a Facebook page, and if you're a Tweet'er, use a unique Twitter hashtag (#yourfoodswap'suniquename) so attendees can connect before and after your events.
Set up your rules as you wish. We decided to keep things simple and only stick with food items that YOU made (not the farmers' market jam mistresses, not the local artisan baker, etc.).
3. Invite your pals over (ones you know and maybe haven't had the pleasure of meeting in real life, yet) and have a big, long table ready for their swap goods. Having attendees RSVP with their projected swap items will also help you plan your host space accordingly.