"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones."
--- Linus Torvalds, 25 August 1991
A long list of ways to help out Open Source - even if you're not a programmer.
Take a look at the Linux system.
You can certainly use Linux without the command line, but learning about it allows you do a lot of really neat things.
A look at some essential Linux utilities.