The drunks over at Modern Drunkard Magazine (yep, that's a real thing) came up with an interesting idea a few years ago. They're based in Denver, so they filled up a chest full of booze, stashed it someplace public in the city, and then created a series of clues which they published in their magazine. If you deciphered the clues (which would make sense only to a Denver resident), it would lead you on a trail that would ultimately land you at the chest, where a bottle of rum and other goodies for drunks was waiting.

If you want to engage people and get conversations started in your community about your product or cause (non-profits, I'm looking in your direction), create a treasure hunt in your community and start spreading the clues. If it works, do it once every couple of months.

It's difficult to get people's attention these days, but creating a puzzle to solve, coupled with a sense of adventure, seems to work pretty well. Call it the "Lost" formula.