Increase Sign-ups with Easier Captchas

Look at this:<p><a href="http://glinden.blogspot.com/2009/05/exploiting-spammers-to-make-computers.html" rel="nofollow">http://glinden.blogspot.com/2009/05/exploiting-spammers-to-m...</a><p>"Googlers Rich Gossweiler, Maryam Kamvar, and Shumeet Baluja had a fun paper at WWW 2009, "What's Up CAPTCHA? A CAPTCHA Based On Image Orientation" (PDF), that asks people to rotate images correctly to prove they are human rather than the norm of deciphering distorted text."

I'm sure there's a way to make users want to enter captchas, like by making it a game of some sort. It would be cool if each captcha was some sort of pun or riddle that the user had to answer. If they don't know, they get another one. It would be kind of fun to know that only clever-enough people could gain access to your site :)<p>(just an idea)

I've always thought that if you're going to insist on repeating captchas, then it would be nice if they varied between attempts. There is nothing more frustrating than being presented with the same completely unreadable captcha-style over and over again.<p>That said, <i>not</i> forcing people to repeat them certainly seems much more humane!