I’m a bot
handrooster.com
handrooster.com
1. Answer a simple math question (e.g. "What do you get if you multiply 5 by 1?").
2. Hidden form field that is supposed to stay empty.
3. Spam word filter ("cialis", "levitra", etc.).
After I put this in place a couple of years ago, the daily number of spam comments my site got dropped from 200 to zero. I was worried that it wouldn't last, but to this day I've only had to delete about five spam comments in total - and they were posted in registered user accounts.
However, if you are implementing a sign-up form for an email service there really isn't a great way to detect fraudulent signups without using a captcha.
That being said, the end game is that the bots will be able to detect anything a human can. Already, they can detect better than elderly or disabled humans. The path to take in this is to get better at automatically detecting behavior we don't want (wether via human or bot) and to block or delete it.
PS: Runs to the patent office...
That's a lie. I find those questions more amusing, but I hope my point is still seen =p