Perl excels at web development. Perhaps have them plan, design, and write their own facebok application?

• Facebook::Graph - santized front end to the Facebook API
• slideshow on the same: A Facebook App in 10 Minutes or Less
• Facebook::Manual further information on facebook application development in Perl
• Developing a Facebook Application for Absolute Beginners has information on the mechanics - signing up for an API key, getting connected to the Facebook application developers community, getting started with the APIss.

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:

• Hacking Maps With Google Map API - dated 2005 but provides a brief introduction that can be a roadmap for looking up other information
• Using Perl for Geocoding - much lengthier denser article.
• Create time availability maps with Perl and Google Earth - provides step by step description of how to gather geographic information, give it map coordinates, and generate the KML file needed to display your own google map page.
• Geo::Coder - various CPAN modules for converting locations into latitude and longitude.
• Geo::KML - tools for generating KML files - Google map's XML markup
• Geo::Google - API for reading Google maps programmatically (does not support creating your own map web page)

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.