Using the mapping tool MAPfrappe, a Texas-based storage search company, of all things, has done us a solid and given us a good look at how San Francisco stacks up in size compared to other cities. Of course we invoke our 7-by-7 (approximate) size all the time, but it hits home with a bit of superimposition. Of course, the missing piece is density — which is listed too. SpareFoot, the storage search company, wants us to think abut space and probably to know what they do, but this is not an advertisement for which they've paid anybody.