A few years ago I started advertising for various intro classes; my numbers did go up after that, although I can't necessarily attribute that to the ads, of course. What I can say is that after I started advertising, people who had never talked to me about CS would ask me good questions about it, even if they didn't end up taking the class (or couldn't). So they have a nice awareness-raising component as well.
- 2007: quotes from/about famous computer scientists
- 2008: puzzles
- 2009: xkcd