An Architectural Yelp?
Avinash Rajagopal dives into OpenBuildings.com:
"Wikipedia tends to be long on technical information and short on architectural criticism. A typical page on OpenBuildings, on the other hand, has all the basic information you might need-contractors, materials, costs, etc.-but it also has the potential to gather opinions, in the form of user reviews as well as links to articles by professional architecture critics."
Rajopal says the site also has an iPhone app in the works so you can read about buildings on the go.