in reply to Bling Bling (or: Teaching Perl to Teenagers)
Perl excels at web development. Perhaps have them plan, design, and write their own facebok application?
Another possibility if the school has liability issues with anything related to social networking might be a google maps application. There are Perl API's for that as well and no limit to the coolness of things you can do with maps:
Disclaimer: I haven't developed either sort of application (yet). These seemed like helpful links to me when I read through them, but I can't vouch for the up-to-date-ness or quality of these links and libraries beyond a look-see.
Update: added link to geo coding modules.