So we've covered our basic needs.
What else does a world need to function? How deep do you need to go?
Religion and Politics. The major headliners. The two generally go hand in hand. Maybe the political structure in your world is the same thing as your religion. Maybe you've suppressed the religions with a overzealous military regime. However you handle it, ultimately you need to understand how these major pieces work in your world. (Or don't work, as the case may be.)
Art. Is it inspired by religion? Or is it more free form? Again. These are just details. Not that you NEED to have art in your book...just that you might possibly need to know the origin of it. And if you have art, the difference between art inspired by religion and art inspired by nature is pretty big, from a society standpoint. (If you want to go THAT deep...)
Weapons. What type of society are you building? What type of weaponry do your people need? Do they buy? If so, from where? Do they make their own? Think of the details of that as well. How does one MAKE a bow? How long does it take to cure a willow branch to make a proper bow arm? How do you even string the thing properly? Or are you going to go the "gloss over route". "Hayden was a master bowman. No one knew quite how he created his masterpieces, but he made the most incredible bows in all of the seven kingdoms." (why are there always seven kingdoms....ever notice that?)
Technology. This one is somewhat tricksy. Personally, I'm in favor of a 'less is more' approach for this one. Unless it's hard Sci-fi. But even then, possibly stick with made up stuff? (IMO). I think the problem with using real technology comes in because things get outdated so blazing fast. You start writing your book on an iMac, and finish on a hologram a year later. But in that book you've put in a reference (or 7) to your trusty iPod. Which is now woefully outdated. None of the cool kids are using them anymore. I think it's best to keep it as general as possible. Get down to the essence of what it is you're doing. rather then using brand names (is that ok anyway?). Say 'Music Player'. 20 years from now when people are still reading your book they'll automatically fill in whatever the new 'music player' is right then.
So. Did I miss anything? What other topics for World Building have you struggled with? How have you kept track of your massive amounts of World Building Research!?