The "Zoo" is designed for human visual processing and classification of galaxies:
... With your help, we've been able to collect millions of classifications, with which to do science faster than we ever thought possible... From now on, if you classify galaxies on the ANALYSIS page, your classifications will continue to be recorded and will be part of the public release, but it won't be part of the first round of papers. Don't be alarmed if the galaxies are odd, this is part of the process of checking our results.
But we still need you! As part of our follow-up work, we need volunteers to review our set of possible merging galaxies. If you're already familiar with basic Galaxy Zoo analysis, click here to read the instructions and click here to take part. Galaxy Zoo 2 will go live in the near future featuring a much more detailed classification system, while further off we plan GalaxyZoo 3 with lots of exciting new data...Most humans are very good at visual classification. This is a return to the original meaning of the word "computer" -- which was a human profession. (Hand calculating logarithm tables, for example.)
After 9/11 mention was made of using humans to view satellite and surveillance and look for "suspicious" images (tall one legged men, for one). Nothing came of that, but classifying galaxies is a happier alternative.