If you remember a few years back, I used this space to do a blog series on Fantasy Worldbuilding. (Saddly, most of the blogs and images did not survive the transition to the new message boards well.)
For the past several months I've been expanding the blogs, editing them, expanding them, and revising them into a book. The PDF is available on the Kindle store and on DriveThurRPG. Soon it'll also be available on the Kobo and Google Play store. (And once the IRS stops messing with this poor Canadian, I might be able to get it on the iBooks store as well.)
The PoD copy will be available on Createspace.com and Amazon shortly.
If you're looking at the new 5th Edition books (or any edition really) and considering making a new campaign setting - or revising an old favourite - look no farther. 200 pages of advice and suggestions with a detailed example world.