Update problems

From what I hear, the people-cracking of captchas are usually done by embedding the captcha from another site into a site for warez or porn, then the customers solve them to 'prove they are human' or whatever without realising they are facilitating spam.

I'd also rather do something custom, simply because it means that automated tools will never be able to crack it if they haven't been designed for it. It's only a matter of time before Asirra is cracked and we have revolutionary advances in object recognition =)