Here are some events that we have done in the past:
Promoting free software
Storming the dorms for Firefox
At Swarthmore we went door to door through our dorms with Firefox installation CDs, helping people install a more secure and featureful browser than IE, while also giving them an example of the power of open source software.
At Swarthmore we have had two very successful LAN parties. Among other things, we
- try to promote free software ("you're still browsing with IE?"), especially open source games. Linux installfests or PC-freeing could coincide with a LAN party, especially if you bring gaming consoles for when people's computers are busy installing stuff.
- show how people repurpose games to make art, e.g. machinima... or even simply interesting game videos like Quake Done Quick.
- share legal content (e.g. CC-licensed or PD material) and shadowy content (e.g. the Grey Album, Illegal Art)
- bring in copyright issues (see how the law makes us all criminals).
And of course we just play games, have fun and geek out in ways that are not related to free culture.