Nightfall
Sage of the Scarred Lands
I'll add my voice to saying Lost Empires is a great suppliment, not just a great Realms suppliment. It really ADDS the background back into Faerun for its history. It's not as detailed as some sourcebooks that were in 2nd edition but for a good summary and a better understanding of each era/place/empire, this is CERTAINLY a must buy for Realms fans and people that enjoy reading sourcebooks for fluff.