While we hate Google for the privacy invasion in advertising, reCAPTCHA is one the areas that is a definite positive. Google has the data and the unique position to make the web safer. I wish they did more.<p>Need to give them credit for fighting: hurting malicious websites by not sending them traffic, keeping search results relevant against SEO abuses, cutting down email spam effectiveness, ... and reCaptcha.<p>All of this becomes very relevant when you run our own online business like I do. You can lament that google knows you're shopping for a new car, but my users lose real dollars if a scammer gets on my website - and google provides the tools to combat this.<p>And, no you can't implement your own captcha. No matter how smart you think you are, you don't have the data that Google does.