Sometimes you just have to take matters into your own hands.
After posting about the difficulty of finding a modern source for choosing a random city or a random river, I went ahead and created:
I took the data from Maxmind’s free world cities database, but there are odd gaps in it. Although the database lists about 3.3 million cities, the population field is blank for all but about 50,000. (Most notably, that field is blank for all but two of the thousands of cities in the Republic of Korea.) My server offers up a random city from among those 50,000. I’m sure I can probably find a list of Korean cities with populations and manually tack them on to the list at some point. [Edited to add: I’ve just done that.]
Now I want to do something similar for river lengths. Does anyone know where to get the data? (No, pawing through Wikipedia’s hundreds of separate lists, for each part of the world and each letter of the alphabet, is not an option.)