I don’t like captcha systems too much, they take you too much time to type unreadable alphanumeric strings, today I found a new project by Carnegie Mellon University: reCAPTCHA and it looks like this:
I like the interface, it could be nice to have only one captcha system for all websites, so visitors wouldn’t have to understand different UI from a website to another.
reCAPTCHA is a webservice and it’s free thus it’s easy to integrate, just a note:
The only reason we would charge is if you are a large corporation that uses a lot of our bandwidth, or if you require special services from us.
How much “a lot” is? I would prefer a clearer contract. Actually I would prefer an open development model.