Ohhhh dear, there are so many.
The Harpers series Carlos is referring to as well as the Drizzt series are Forgotten Realms books.
I don't know how much you know about this Fantasy Realm. It is a world created for use in the Dungeons and Dragons role-playing games.
Of series worthy of our attention is:
The Avatar series.
Shadowdale
Tantras
Waterdeep
Prince of Lies
Crucible: The Trial of Cyric the Mad
They're most definitely good.
Sembia series
The city of Selgaunt teems with all walks of life -- merchants and assassins, mages and thieves, priests and heretics. The fate of the noble Uskevren clan is bound up in the intrigues and shadowy dealings of the city as, one-by-one, the family members discover their own destinies.
The Halls of Stormweather
Shadow's Witness
The Shattered Mask
The Netheril Trilogy
In the far distant past, great cities floated above Faerûn while master mages spun their spells and mighty sorcerers challenged the gods themselves for dominance.
Sword Play
Dangerous Games
Mortal Consequences
The Cormyr Saga
A sweeping historical trilogy about the land of Cormyr and its generations of mighty wizards and noble kings.
Cormyr: A Novel
Beyond the High Road
Death of the Dragon
Now this list is by no means complete. I believe more books have been published in the Cormyr saga since this was written. (I merely copy/pasted from another website - I know, I'm a cheat)
A complete list of the books published for Forgotten Realms (FR) can be found here:
http://www.wizards.com/default.asp?x=books/fr/bibliography
But take note that this list also includes rulebooks, sourcebooks, and accessories for us D&D gamers.
Here:
http://www.wizards.com/default.asp?x=products/list&brand=All&year=All&type=Novels
is a list with the novels that WotC have published. It contains FR novels as well as Dragonlance, Magic: The Gathering, and Greyhawk.
Should you wish to know more about this world feel free to ask - even drop me a line - being a regular gamer I'm sure I can find answers for quite a few questions, and if I can't, I probably know someone who can.