Lovecraft, Forgotten Realms, and Dragonlance is of course game (all have AD&D material out there already - I recently got my hands on Lovecraft stats
).
Tolkien, as the progenitor of medieval fantasy as we know it (and who profoundly influenced AD&D as a result) is of course good as well...
But we'll see
(Not sure what use I would have for Great Old Ones or Caramon in my game...)