Funny Captchas

Spam is an omnipresent problem on the Internet these days. Not only email is affected with approximately 100 billion Spam mails a day, but also search engines, instant messaging services, forums, and blog comments.
One temporary solution to reduce Spam in wikis, forums and blogs are reverse Turing tests or Captchas (Completely Automated Public Turing test to tell Computers and Humans Apart).

Captchas are little tasks you have to solve in order to prove that you're human. Most of them display some distorted and noisy letters that you have to identify and reenter to pass.
For now these Captchas cannot be handled efficiently by computers; as such, the spreading of Spam is reduced drastically.

Funny Captchas on the web

However, there are some very strange Captchas on the net. Some of them unintentionally offend you (e.g. the letters read as "fuckoff"), some of them are indecipherable, and others expect too much intelligence from the average internet user.

Here's a list of funny Captchas on the web.

A rather complicated Captcha

But don't think that Captchas will be a permanent solution to comment and forum Spam. You can easily hire a bunch of low-wage workers and let them solve these tasks for you. Or even cheaper: Create a porn or warez site to attract traffic and feed the challenges to clueless humans who want to enter.

In fact, that's kind of what reCaptcha does...

Stop Spam – read books

According to reCaptcha's site around 60 million Captchas are solved every day. If every challenge takes 10 seconds to solve you end up with about 160.000 hours a day. Time that might be used for something useful.

The reCaptcha project uses this time to digitize old books, that are resistant to OCR. So, instead of random letters real words from real books have to be identified. With this, word by word, complete books from the Internet Archive will be digitized.

reCaptcha in action.

Everybody who wants to support this can use reCaptchas-API for free. Many CMS's and blogging systems like Drupal, Wordpress or Serendipity allready support reCaptcha via plugins.