Does anybody know where can I find a good system to generate those images used to verify if it is a real person that is filling out a subscription form?
I did one of those for a column [stonehenge.com]. It's rudimentary (and was trivially reverse-engineered in a posting at Perlmonks [perlmonks.org], but it would fool 98% of your visitors (and confound the other 2%).
check out (Score:1)
Been there, wrote a column (Score:2)