Every time I think that “it would be nice to have a website that… (insert nice thing here)” it’s already there. Last time it was the music recommendation system. This time it’s about “collaborative travel guides”.
I’m not very fond of travel sites like Virtual Tourist or Trip Advisor, because the information in there is organized around users rather than topics. However the fact that the content is provided by people based on their travel experiences is a clear value (plus it’s free). So I thought that there should be a community-driven site, but formatted as a travel guide - sort of a “wikipedia for travels”. Sure enough, typing “collaborative travel guide” in Google revealed at least two sites that are exactly what I just described.
World66: The World66 project’s motto is “We believe that travelers are the best source of travel information”. They currently have 77,692 articles on 19,914 destinations all over the world.
WikiTravel: Wikitravel is a project to create a free, complete, up-to-date and reliable world-wide travel guide. So far they have 8,667 destination guides.
Apart from the numbers, in general I like World66 design better, but WikiTravel tends to have more exhaustive information (although it’s often lacking a map). It’s difficult to make a fair comparison because the quality and amount of information relies on how many writers contributed on a particular entry. For example, I would have liked to compare what they have to say about my hometown, Lucca, but WikiTravel in practice has no information on it yet. The respective entries on Helsinki may be more signifcant. You draw your own conclusions 
Helsinki on World66 - Helsinki on WikiTravel