In an interesting bit of trivia, which I just discovered, some people believe Cthulhu might have actually originally been a name that Lovecraft dredged up for Nergal; the theory goes that Cthulhu was actually a deliberate mispelling/adoptation of the word Cuthalu, which means "man of Cuthah" which was the underworld city where Nergal resided as well as the name of the real world city where his cult was strongest, and was therefore a title of his.
Very cool. What's your source for this? I've been a Lovecraft fan for a long time, and I'm always interested in reading something new about him.