Yunix is a service that hopes to be able to provide users with free shell accounts.
Of course, there are more potential uses than that. If there is something you would like to do but are unsure of how, or if a package is not installed, then you should make a post in the forums or ask (politely!) in the IRC channel.
How do I join?
Glad you should ask! An IQ test is required. It's not hard. Think of it like an easter-egg hunt. Follow the clues and find the goodies!
Firstly, if you haven't done so already, you'll need to sign up for an account at the yunix.net website. This process requires human intervention so you will need to be patient. Make sure your email address is correct, as you'll need it to receive your activation email.
Once you have registered and been activated, you will be given access to more information (on the website), and you will be able to post in the forums as well. Further information on how to request an account will await you there.