Google today announced Knol – an alternative to Wikipedia that promises to pay authors.

Getting Google’s advertising onto more and more pages is key to the company’s growth. Wikipedia poses an obstacle to Google’s growth, though, because it’s ad-free and quickly becoming becoming the most popular source for information on all sorts of topics.

To fight this, Google is creating Knol – an alternative to Wikipedia that offers revenue-sharing with authors.

Here’s how Google introduces the site:

The web contains vast amounts of information, but not everything worth knowing is on the web. An enormous amount of information resides in people’s heads: millions of people know useful things and billions more could benefit from that knowledge. Knol will encourage these people to contribute their knowledge online and make it accessible to everyone.

The key principle behind Knol is authorship. Every knol will have an author (or group of authors) who put their name behind their content. It’s their knol, their voice, their opinion. We expect that there will be multiple knols on the same subject, and we think that is good.

With Knol, we are introducing a new method for authors to work together that we call “moderated collaboration.” With this feature, any reader can make suggested edits to a knol which the author may then choose to accept, reject, or modify before these contributions become visible to the public. This allows authors to accept suggestions from everyone in the world while remaining in control of their content. After all, their name is associated with it!

Knols include strong community tools which allow for many modes of interaction between readers and authors. People can submit comments, rate, or write a review of a knol. At the discretion of the author, a knol may include ads from our AdSense program. If an author chooses to include ads, Google will provide the author with a revenue share from the proceeds of those ad placements.

With Knol, Google is looking for a way to monetize user-generated articles, effectively paying you to create a Wikipedia-killer.

It’s not much of a leap to think that Google will duplicate this approach with other content, sharing revenue on news or how-to videos, for example.