Legoboy and belrix both have Heroscape Clubs at schools, apparently very successfully. Legoboy has a bunch of pictures from his
5th Grade Club, and blerix says they get around 20 kids (20!) in their group. As you can see in the "Similar Thread" guide below, there's been a lot of people who tried it out. War games and miniature games don't have the stigma of RPGs, for various reasons, and seem a lot easier to get clubs going.
Good luck, Tiranx!