In a nice bit of Christmas news for the OSR, the 1983 boxed set of the World of Greyhawk is avaliable on PDF again. You can get it here from DnD Classics website, RPGNow, or DrivethruRPG.
While I known for promoting the Wilderlands and hexcrawls, I started with the World of Greyhawk for the first couple of campaigns I ran after getting the DMG. As a fan of Tolkien appendices in the a Return of the King, I was impressed with the epic sweep of history in Greyhawk. The fact the Gygax had barbarian migrations as a major component alongside elves, dwarves, orcs, etc was impressive to me back then.
The only downside was that I never thought that religion got the same type of detail. Instead we got a hodgepodge focused on the deities not the religions. Well I fixed that for myself with this article on Greyhawk Gods.
I hope everybody had a Merry Christmas and I hope you all have a Happy New Year.