Spam Prevention Techniques (ideas)

So I've been thinking of various spam prevention techniques, from stats & NN to NLP, but, how would you all feel about textual challenge questions?

Either questions I can make up in my spare time about programming (i.e., "Lisp is a ____-level language."), or textual captchas? So you could still post through links or whatever, and nothing would ever leave my server, but it would make it a lot harder to automate posting.

>>11
Fuck off you little white queer. I can't wait for the pigs to throw your tight CP-possessing ass in jail where your alpha cellmates can expand it way beyond what drugs did to your mind.