Creating NPCs from 253 by Geoff Ryman

I am currently reading 252 by Geoff Ryman and I have found this a surprisingly great resource for NPCs.

For those that don't know, 253 is a story a page of every passenger on the London underground train between two stations at one particular time. Each page is devoted to their appearance, who they are, and what they are thinking.

Each character is short and interesting enough to translate into a character in a session.

What other books have people found as useful for creating small but non insignificant NPCs?