D&D fantasy is a mature genre and so has a lot of cliches and overused concepts that plague it. But in my opinion there is still value in the original concepts when boiled down to their essential elements. In my own experience, to read of or hear about a cliche is very different from actually playing through one, and doing so can be surprisingly fun and evocative. So lets build a setting post by post trying to use the most "classic" elements possible while also trying to put a creative spin on the idea, or make it fit D&D better.
You can post about whatever you want, an idea for a campaign within the setting, a country, a civilization, a race, a continent, world, a planet or even plane. I think classic fantasy extends even to the things we might consider cheesy, like aliens in flying saucers, fairy kingdoms, time travel, and gods of light and darkness battling at the beginning or at the end of the world.
I'll begin with a D&Dified take on Sauron, which I'm not sure I've ever really seen:
The Necromancer is a lich who rules from his Dark Tower in the North and once led an army of monsters to conquer the world, but he was stopped by an Alliance of races (all the races in the player's handbook) and was ultimately by a Paladin Hero who wielded one of the five Holy Avengers. However, unknown to all, his Phylactery remained and would regenerate the Necromancer in time if it was not stolen from the Frozen Tower in the wake of his defeat by a mysterious Mad Wizard. The Necromancer dares not to regenerate himself while his Phylactery's location is unknown to him for fear of a trap, and so he waits, communing with his lieutenants by portents and visions and sending his nine death knights to scour the land for the Mad Wizard to secure his Phylactery so he can return to this world and begin anew his war to dominate all life. The identity and intentions of the Mad Wizard is a mystery to all, but the forces of good must find him and destroy the phylactery he stole in order to end the Necromancer's evil once and for all.