Captchas are ineffective for the most part, they're easily beaten by scripting - to the extent that they're actually more annoying for legitimate users than any semi-competent spammer. The new user process requires verification - there is a human being at the other end patiently adding new accounts for spam that ends up on the site for a couple of minutes at most. Why they find this valuable, I do not know. I have asked the developers for more effective filtering, but so far nothing. I'd rather not complicate the signup process further at the expense of legitimate users, especially as there's very little can be added that would genuinely separate proper users from spammers.
Is it possible for the devs to make it so that the new user process is something like: * Create new account as it is now * Post a question * That question has to have a comment, or a vote, or an answer, or be checked by a mod * Then the user is given freer rein to post more questions Obviously, allowing while still allowing new users to answer questions, make comments, do whatever else they can do now?