The absolute best way we've found to grow your AdBoards is to integrate them in one or more of our downline-builder websites. Right now we have three that use AdCardz as one of the built-in traffic sites, and you can set any of those sites up to use your own AdBoards...
Then as you promote our downline-builder site, you're also promoting your AdBoards to loads of new Advertisers, who will automatically keep the viral process going, working even harder than if they just found your AdBoard some other way.
Be sure to check out EzHitzs, EzBanEx, and EzTraffic while you're here. Any of these will give your AdBoard a serious boost. Even better, use a different AdBoard in each, and promote them all!