panoramas
Although the ACES team members are pretty much stuck here in Redmond (with one or two telecommuting exceptions), we build a product that simulates the whole planet. Team members come from all over, and we've done a lot of world travelling, but we still spend an inordinate amount of time doing research on the web.
Recently Flight Simulator has seen the number of people who do terrain texture add-ons explode. I think a lot of that has to do with the amount of aerial and satellite imagery coming on line. When I started (way back in the Dark Ages) I had to make a trip to Juneau to go through a company's archive of a million or so aerial images. I then had to make my selections based off looking at reversed negatives, and a few weeks later we got color photoprints. Contrast that to what's now available, and you can understand the renaissance Flight Sim is undergoing.
It's not just terrain of course, it's also landmark objects. So it's always nice to come across great reference sites that show a bit of both:
http://www.arounder.com/
