good question (Score 1)

Well... I'm a homeschooler / cc student, but am in your target age bracket. Most of my friends are heavy-duty nerds, so I'm nto sure how much I can help you with appealing to the general population of HS-ers, but here's my $0.02: Games are good. The fascination with making things move across the screen is not be undestimated. When a guy showed up at the gamestore for a D&D session with a scientific calculator and a tiny moving caracter program on it, any and all of the uninitiated were swift to come over and oooh and aaah. HTML is very cool, too. Although it's fairly outdated by web design apps, people like making web pages. HTML was my first introduction to any kind of computer language, if you would call it that. Also, anyone with a livejournal can benifit from knowing even a few tags... even simple things like italic brackets. Robots will only draw the serious techies. It's such a stereotypal nerd-fair event. In closing, I'd suggest a programming event. Try very, very hard to keep the focus away from the "geek factor" of the event. The more you have, the less people will come.