While actually dealing with the entire planet rather than just cities, AlertMap is a really interesting site. It displays, in real-time, all the disasters that have befallen the Earth recently (and it is extremely comprehensive too). The WSJ had an article about it where you can find out more.
Awhile back, the Skyscraper Museum in New York City had an exhibit entitled BIG BUILDINGS. This exhibit, with an extensive online component, explored the history of really big buildings. Two categories, based on research, were created for these large structures, called Jumbos and Super Jumbos. These are buildings that are extreme, both in height and volume, relative to when they were built. Here is the Jumbo calculation methodology and here are the Jumbos and Super Jumbos built since 1950 (as of 1999, when the exhibit was held). Lots of good pictures and data for the skyscraper enthusiast.
About a month ago, I discussed the Heat Island Effect (where cities are warmer than their surrounding areas). Well, it turns out that this phenomenon has affected the evolution of the organisms that live in cities, or at the very least, ants. In their paper Urban Physiology: City Ants Possess High Heat Tolerance Angelleta et al. demonstrate that urban ants have a higher heat tolerance than rural ants. Further studies will have to be done on city mice and country mice.
The CDC is planning to scale back its main disease surveillance system, BioSense, and will now only focus on tracking diseases that occur in the largest cities in the United States. While this might be due to budget cuts, this strikes me as a foolhardy decision. To focus only on the larger cities is to miss the sources of possible outbreaks. While in decades past this might have still provided enough time to stem the outbreak, nowadays, when travel is routine and widespread, epidemics can spread to the entire United States extremely rapidly (here are some flu simulations, for example). By limiting detection to only large cities, this might remove the element of early-warning and possibly make it too late for proper counter-measures (by the time the outbreak is detected, it has already gone national or international). If the CDC has done simulations and studies that show that the lead-time gained is negligible, that would be good to know and would assuage my concerns, but I have not heard anything about that. If you are aware of anything like this, please let me know.
Braess’s Paradox, named after Dietrich Braess, is when you add roads or capacity for cars, and thereby worsen traffic (or alternatively, you lower traffic costs by removing roads). Formally, this simply means that the current traffic equilibrium state is not the optimal one. Dietrich Braess, on his website, notes that this concept has applications to computer networks in addition to traffic networks.