Google has decided to continue its bid for world domination by introducing Google Knol, where the company will "encourage people who know a particular subject to write an authoritative article about it" - sound familiar? The name Knol stands for a unit of knowledge, and Google's service differs from Wikipedia in that users will not edit each other's articles, instead they will write individual knols which compete against others written about the same subject. Another major difference between Knol and Wikipedia is that if the author chooses to let Google include ads with their knol, they will receive a "substantial revenue share" of the money that Google makes from the ads. So basically, Google is trying to encourage users to write encyclopedia entries about a subject by offering them a financial reward in return. At present the tool is still in the first phase of testing, and you only join by invitation, but Google eventually plans to let everyone use Knol for free.