Use the press.
Get offline with this stuff and nail a group of people who won't see it coming. Not only will you get mad new biz from this, but you'll also get people who want to promote your service.
I'm not talking about one of those idiot SPAM press things everyone blasts through PRWeb and stuff, those are semi cool, but way over done.
#1: call your local newspapers, ask for the biz editor. Hit them with something interesting like how you're going to be teaching high school students to develop websites for free in an online seminar and you'd like them to do a story on it.
#2: hit them with a press release talking about this.
#3: Follow up. (this is almost more important than the first phone call!)
#4: Lather, rinse repeat.
This works for TV/Radio/Paper and online.
However, as you're not selling anything... you're giving quality, people will open up and be more attracted to your business.
#1: more money
#2: people will want to promote you
Hope that helps!