A wiki travel guide. At the moment it seems to be composed of steals from the CIA world fact book. But if it takes off it will be interesting. Can it work? Or is there too much scope for abuse by hotels, regional tourist boards etc?
Maybe it can be policed? Are spammers controlable by honest citizens? I guess the problem is participation rate. Unless there's also some kind of regular discussion, travelers who know a place are unlikely to visit it's page regularly. Whereas spammers have an incentive to spam regularly. OTOH couldn't the same have been said about those who want to use Wikipedia to spread-some kind of disinformation?
Maybe it can work well in conjunction with Free accomodation exchange networks