Chimpsky is a web application for the detection of duplicated content and web-derived content in text files. It works internally with plain text only, but it will automatically extract text from files in PDF or common word processor formats.
Chimpsky is named after Nim Chimpsky, a famous proband in studies on the language abilities of primates. Apparently, the argument whether Nim Chimpsky really had some concept of language or merely faked it is still ongoing.
The quotes that are displayed when mousing over the chimp face are taken from wikepedia.