Increasing Returns and Economic Geography (pdf) was, I think, my best academic paper; economists apparently think so too, putting it at the top of the list on Google Scholar. Now Charlie Stross, my favorite contemporary science fiction author, takes on the issue of increasing returns and their implications for, among other things, the possibility or lack thereof of space colonization:

Space colonization? Get back to me when you’ve tracked down how many people it takes to design and build a space suit. (The number is in the hundreds, if not the thousands.) More realistically, we won’t have autonomous off-world colonies unless and until they can cover all the numerous specialities of the complex civilization that spawned the non-autonomous, dependent-on-resupply space program. Or, to put it another way: colonizing Mars might well be practical, but only if we can start out by plonking a hundred million people down there.

Go read. And while you’re at it, read Henry Farrell’s related post on technological retrogression in societies with too few people.