I recently signed up for a trial of SmartSheet (review forthcoming), and it took me three tries to get past the "captcha," the distorted numbers and letters I had to type to prove to the sign-up system that I was a human.
I'm a person, dammit. You can tell because I'm cursing at the screen. If you make the text any harder to read I'm going to take my personal business elsewhere. Then you'll have nothing but the robots to keep you company.
Related: I also tried to get my new laptop setup on the cellular network today, which required calling up the carrier and reading two long strings of digits off the bottom of the laptop that were so small I needed to use my glasses like magnifying lenses. Since the numbers are embedded in the hardware, why couldn't some software send it over the Web and sign me up that way?