I blogged in December about how fast growing web sites are often fueled by user content. Users post content, which attracts more users (as search engine index this content), who in turn post more content.
Today I discovered a new Idealab company called Insiderpages that is focused on the local yellow pages market. All the local listings are created by users. "The yellow pages written by friends", it says. Launched in November, the site has a 1 week Alexa ranking of 50,000, which is excellent for such a new site.