I've used the CC license and recommend it.

I frequently run into the misunderstanding that "open source" is the same as public domain, and the structure of the Creative Commons licenses helps clear that up, because it's so much simpler than the GNU and MIT licenses that encumber most software. The core fact is this: You have to retain ownership over something in order to place terms on its use. CC and open source require you to retain the copyright, otherwise any terms you try to enforce are just vapor. As long as you have the copyright, you're then free to say "now knock yourselves out, as long as you credit me".

I like that there's a menu of CC license terms. I'd compose one for the Zone, and works of more historical significance like King's speeches, that allows reproduction with credit, but prohibits modification. That's how finely CC dices it, plus there's an escape clause to add additional terms (I used that one to write a license for a MOOC a year ago).