Get huge team stickers to fit on your car door panels. Include your team website address (note, this requires a team website) on the sticker so people who see your "team support vehicle" at races and events can find you. Bonus points if that vehicle is a van or wagon.
Start up a junior division in your club. This brings in not only young members who might be around for a long time, but frequently their fathers too.
Train in groups with your club jerseys on and be friendly to people you pass by.
Have an EZ-Up with a team banner set up at events where your members can warm up on trainers. Have club information on pamphlets or papers ready to hand out. Free shwag (especially if you can get it for free) attracts people. Massages, sports drinks, energy bars, anything a sponsor is willing to provide.