The idea is to provide ProjectGutenberg? with public domain ASCII e-texts of classic literature. To this end, facsimile images of book pages are scanned and OCRed. But before the OCR text can be published as an ASCII e-text, it must be proofread, which is manual labor, and very boring, especially if you know you have 500 pages in front of you.
So this website allows anybody to register and pick a page at a time, viewing the facsimile image and using a web form to edit the OCR text at the same time.
It's almost like a wiki, for its openness and online editing, but not quite. Some of the differences between a wiki and DistributedProofreaders:
It is intriguing to think about these differences and how they could leveled by copying ideas back and forth. What would the resulting website be like? In fact, two other e-text projects already run prototypes for similar systems, where the facsimile images are published as part of the output product, and users can fix errors as they spot them. These projects are the Christian Classics Ethereal Library (http://www.ccel.org/) and Project Runeberg (http://runeberg.org/). The latter was founded in 1992 by LarsAronsson.