Online encyclopedia Wikipedia has long been a strictly non-profit service, but that doesn't mean that unofficial spinoffs have taken a vow of poverty.
One promising wiki project that is based on Wikipedia's guidelines and software is Wikitravel, which formed a partnership a few months back with rival site World66. Both offer a type of wiki-operated challenge to mainstay publications such as Fodor's Travel Guides, analogous to what Wikipedia has done to undermine the dominance of Encyclopedia Brittanica.
The key difference: Travel wikis are planning to turn a profit.
Even wiki naysayers would have to admit at least some potential for social-networking sites in the travel industry. Online services have presented serious competition to brick-and-mortar travel agencies for years, and the popularity of sites like Tripadvisor proves that people value community input and ratings. All of which could be why Google is following Yahoo and others down this path.
Wikis bring even more to the party. Many of today's community travel sites are rich in content but require readers to wade through dozens of postings and calculate a rating on their own; wikis--if they work correctly--can provide consensus reviews that can be read and navigated easily in a single place. Moreover, as Rafe Needleman pointed out in a recent post, people love to document their trip experiences and could therefore provide even more interactive components to a new generation of travel services that offer more specific information than ever imagined.