Urbanspoon has added Chicago and New York to the set of cities they index for restaurant reviews. If you love food and live in those cities, give them a try; the site is a great resource. (Berry411 hits include links to Urbanspoon results where available; this now includes the new cities.)

An interesting new Urbanspoon feature is cities at night, an interactive visualization of restaurant distribution in a city:

Sometimes you just blunder into a new feature. When we were setting up New York and Chicago, we thought it would be useful to have a visualization of all the restaurants in a city, divided by neighborhood. This was just to spot errors in our data.

Funny thing is, it looked really cool. At least to us. Kind of like flying over a city on a dark night, except only the restaurants have their lights on. In New York, for example, we have over 23,000 restaurants and it’s amazing how well the shape of the landscape and population density can be revealed with just restaurants.

So we decided to put it out there for you all to play with. Here’s the “night-time” view of Chicago, New York and Seattle.

Adam tells me some very interesting stories about the challenges they faced in normalizing the indexed data; with any luck he’ll blog about some of the tricks they employed (without giving away too much secret sauce.)