Like choose your-own-ending novels and BASH? What would you do if you suddenly had ssh access to someone else's server? This is a really fun corner of the net. Excellent resource/trainer/time-waster. When I talk to people from the DIY linux/selfhosting/FOSS communities, many folks haven't heard of it.
What other cool stuff do you know about? Think it sucks and want to tell me why?
Note: I am not at all associated with this project - just think it's a valuable stop on the good 'ole internet.