NASA Clickworkers is a Citizen Science project using amateurs for scientific data input.
Wikipedia article at http://en.wikipedia.org/wiki/Clickworkers
Yochai Benkler in the Wealth of Networks
"NASA Clickworkers was "an experiment to see if public volunteers, each working for a few minutes here and there can do some routine science analysis that would normally be done by a scientist or graduate student working for months on end." Users could mark craters on maps of Mars, classify craters that have already been marked, or search the Mars landscape for "honeycomb" terrain. The project was "a pilot study with limited funding, run part-time by one software engineer, with occasional input from two scientists."
In its first six months of operation, more than 85,000 users visited the site, with many contributing to the effort, making more than 1.9 million entries (including redundant entries of the same craters, used to average out errors). An analysis of the quality of markings showed "that the automatically computed consensus of a large number of clickworkers is virtually indistinguishable from the inputs of a geologist with years of experience in identifying Mars craters." The tasks performed by clickworkers (like marking craters) were discrete, each easily performed in a matter of minutes. As a result, users could choose to work for a few minutes doing a single iteration or for hours by doing many. An early study of the project suggested that some clickworkers indeed worked on the project for weeks, but that 37 percent of the work was done by one-time contributors." (http://www.benkler.org/Benkler_Wealth_Of_Networks.pdf, pp. 69+)
See the entry on Citizen Science