I tend to agree with proponents of the grass roots approach to fostering growth in the hobby. To borrow from the environmental movement, "Think globally, act locally."
Some specifics?
-- Look for ways to attract people who might be interested but otherwise not exposed. Most of us have a weekly game played at someone's house with a small group of people. Nobody except other gamers are likely to ever find out about these sessions or be invited. Instead, consider organizng more of a local club that gathers area gamers and creates an opportunity for non-gamers to get involved. Organize local gamedays at a neutral, welcoming place like a community center. Private homes and, unfortunately, most local game stores tend to scare off non-gamers. (By the way, if your local FLGS is not a welcoming place, encourage it to become so.)
-- Publicize locally at no cost. Most local papers include community activity listings; get your group in them. If you're doing something in particular (like a gameday), invite the local press to see what's up.
-- Run games for youth. Want new blood in the hobby? Run a game for kids at your local high school, middle school, community center, church/temple/mosque. Encourage teachers to see the value of gaming. GAMA runs a program called "Games in Education" that includes inviting teachers to Origins. Check it out and do the same for folks in your own community.
Lastly, be constantly aware that in the eyes of the general public, our hobby remains synonymous with socially inept, out-of-shape, unambitious, unsuccessful, reality-deprived, live-in-the-parents'-basement losers. Sorry to sound so harsh, but that's how pop culture sees us. So if you want to expand the hobby, be constantly vigilant about busting up that stereotype.
Carl