Every week, when I post a blog or other comments, create a new online account, etc. I have to solve a few CAPTCHA's which are mainly used to make sure real people, but not bots, fill in HTML forms to prevent spams. It works on the assumption that it is hard to solve CAPTCHA's in difficult-to-read images by computers. What if you get a pool of people to solve them for you? I came across this interesting post where there's actually a market for solving CAPTCHA's manually. This could be used for both good and bad purposes. I didn't know people solve them for money!
Customer: I want to get xxx number of CAPTCHA's solved.
decaptcher.com: Not a problem. We charge $2 for 1000 CAPTCHA's and minimum deposit is $8.
Customer: Wow, it's only $0.002 for a CAPTCHA!