Add speech synthesis and this would be an awesome camera for the blind.
> VizWiz is an iPhone app that allows blind users to receive quick answers to questions about their surroundings. VizWiz combines automatic image processing, anonymous web workers, and members of the user's social network in order to collect fast and accurate answers to their questions.
Lots of people who become visually impaired later in life can't read Braille as their fingertips aren't sensitive enough, especially if they did manual work earlier in their life. Working out a picture is even harder.
As a side note about this, William Moon invented 'Moon script' which was a kind of simplified alphabet in embossed writing to help visually impaired people read. It was invented a little before Braille invented the raised dot patterns, and even after Braille became popular, Moon still had it's niche for those who didn't have the resolution for Braille. As Moon was based on the Roman alphabet, it was also easier to learn for people who'd been able to read then lost their sight.
Someone (the "turk", or whatever Amazon calls them) keeps an open window (and is optionally paid for each minute with the window open), so new HITs would appear immediately, and the "turk" would be rewarded based on the speed of the response.