Beyond the normal advertising push thing, specific events that people will travel for work well.
When I was a Wargamer, and ran Clan War events, people would travel fairly long distances to play in some of the Tournaments I ran. Granted, the game was not highly popular, but it meant that when a sanctioned tourney did happen, people came a lot further for them.
The Double Exposure NCC is a way of doing this, of course - the trick is to get word out to those groups that are ceneted on the product, not the location. That is, get word out on the mailing list for Game X, as opposed to just the stores in Town Y. With a focus group, like a game's mailing list, you will be reaching people who you know are interested in what you're selling, instead of just random shoppers.
No one avenue will do the trick, but the more you find, the better off you'll be.
