wikiHow Jack Herrick, the founder of wikiHow, a how-to guide built on the same open-source software as Wikipedia, is hardly the only entrepreneur inspired by the efficiency and low cost of what has become known as the wiki model.

Although Wikipedia is operated by a nonprofit foundation, ideas for advertising-based wiki sites are beginning to take their place alongside blogs and social networking sites as a staple of Silicon Valley business plans.

In addition to Wikia, a site devoted to topics judged too esoteric for the online encyclopedia, there is ShopWiki, for product reviews, and Wikitravel, for tourism advice. Several start-ups allow users to operate their own wiki sites.

Read full story