Since people really have no way to know what kind of challenges you offer, it would be good if you had some screenshots/demos on your homepage instead of a generic "private beta" page.
You also might want to think about doing things like Google's image rotation captcha experiments. I was really excited when they announced that they were playing with those because I was hoping they'd kill traditional captchas. Here's a PDF of a paper by some Googlers: http://www.richgossweiler.com/projects/rotcaptcha/rotcaptcha...
Since people really have no way to know what kind of challenges you offer, it would be good if you had some screenshots/demos on your homepage instead of a generic "private beta" page.
You also might want to think about doing things like Google's image rotation captcha experiments. I was really excited when they announced that they were playing with those because I was hoping they'd kill traditional captchas. Here's a PDF of a paper by some Googlers: http://www.richgossweiler.com/projects/rotcaptcha/rotcaptcha...