inside elevation by parramitta (cc by)
Why does Wyoming have such a low population compared to neighboring states? barchan explains, jeb adds: "everything in the West comes back to water".
Ever wonder what a "nor'easter" is? Check out the great answers from Seymour Zamboni, plastic_animals, and weathergal in rules of thumb for weather patterns in the USA.
Lots of different places have unique colloquial weather terms too. (Gullywashers, the foxes' wedding, and lots of wind terms again from barchan.)
Also in language surveys: What are some antiquated place nicknames (like the Borscht Belt)? What do other languages call it when your foot "falls asleep"?
Different cultures also have their own languages of flower-meanings. Plus some cool info from sukeban on how new imported flowers like roses made their way into kimono designs in the late 19th century.
For geography/history detectives: How can I tell, just from clues in the document itself, when a world map was made or figure out when a photograph was taken?
Did you see the new photos from the formerly-hidden-from-visitors North Korean subway system?
Some great answers in travel threads recently: Italy: non-traditional but amazing?, and also Scotland: what not to miss.