Nagas are snakelike creatures, and are, by and large, rather evil. They inhabit the dark and dank parts of the world, using their strength, cunning and magical ability to keep lesser creatures in thrall.
Nagas, like Liches and Beholders, fit in nicely as an enemy in almost any campaign - their predilection for evil and accumulation of underlings serves them well as a "final boss" sort of character. Their name is taken from a variety of snake-spirits in eastern mythology, the Nāga, which also lend their name to Voldemort's pet snake.
Another relative quickie this week, I have plenty to do! I think next week we're going to be doing some more requests.