If you're one of the few people who has ever felt the urge to comment here, you'll probably have noticed that I don't have a captcha here. I used to, but haven't had one for ages.
You'll also have probably noticed the amazing amount of spam comments I get. Look at them, all of them!
That about sums up my feelings on captchas: they're useless. They're not needed to prevent spambots, and they get in the way of real people. Some of them are particularly bad - about 1/4 of the time, I can't read the captcha and get flagged as a bot.
Well, now there's an even more stupid and less reliable way to detect bots, developed by Microsoft:Animal Species Image Recognition for Restricting Access.
There's a demo on that site. I fail at least half the time. Useful!