If you’ll let me get away with comic books as “literature”…
Green Lantern
If not, then many of the previous options sound good.
I’ve got it…an Asimovian roboticist. 'Nuff said.
The Great Will of the Macrocosm, from Excel Saga (well, if you count a comic book/animated series whose main premise consists of pop-culture parody and severe wrongness as “literature” :D)
Because being able to reset the Univerese is such a kickass power.
No, I think a late-model Asimovian robot would be more interesting. R. Daneel would be a good choice.
Or maybe a Go-Captain, or even better a native of Norstrilia, from Cordwainer Smith’s works.
I believe that’s King’s Dark Tower series.
Can you ID mine? 
A Red robed Wizard (Krynn, before they mucked it up with this 5th age garbage)
One of the group from Vampire$ (the one that spawned that interesting movie…)
Interplanetary Settler, on Tellus Tertius.
Any one of a number of characters from the stroke books I read as a kid… hehehhe…
And, from a television show…
Being a Q would be the ultimate. Hehehe…
Two characters come to mind:
Mycroft Holmes (Sherlock Holmes’ brother)- His ability to store and retrieve facts memorized by just reading.
Professor van Dusen (The Problem of Dressing Room A - Jacques Futrelle)- Known as “The Thinking Machine”. 'Nough said.
Both abilities would warrant an occupation that is away from the dullness of everyday life, but quiet all the same. Something like the Diogenes Club would suit just fine. They would have to have an internet connection though 
Damn you Gadfly and Diogenes – you beat me to it.
Oooh, can I be the Pedro to your Will-chan?
Failing that, I’d take Nabeshin.
A few choice answers:
-A top-ranked wizard in the lands surrounding the River of the Dancing Gods, from the books of that name
-Mavra Chang, travelling around with Obi (from the Well of Souls series)
But the bestest answer:
-An Angel of Samaria. (From Sharon Shinn’s Archangel and its sequels)
-You’re incredibly strong and immune to all disease
-You can FLY
-You have an extremely useful and rewarding job in which you actually spend your time making people lives’ better
-You’re rich
-Mortals are constantly vying to sleep with you
-You get to spend lots of time singing
Navigator on one of the spacecraft in one of Heinlein’s science fiction novels.
Resident in Pogo Possum’s comic strip version of the Okeefenokee Swamp (sp?)
I think it would be so cool to be a Battle School Brat from Ender’s Game!
I would also like to be a member of the Murry Family from the “A Wrinkle in Time” series.
A HAL type computer from 2001: A Space Odyssey.
I can try…
Nah, the Old Blood from the Six Duchies is Hobb’s Farseer series … and I guess I wouldn’t mind that.
I’d definitely like to be an Aes Sedai – but one of the cool ones, not the pain-in-the-ass, wanna-rip-off-their-arm-and-smack-them-with-it caliber.
And a Jedi, of course.
Or possibly one of the sidhe from Laurell K. Hamilton’s books.
Or maybe Supergirl.
A mutant, but only if I get a really awesome power so I can join the X-Men, wear spandex, fight evil, and angst.
HOW could I have forgotten that?
Sheesh how silly of me. I think that would just edge out Dragonrider for me. But only just.
Appealing… but I dunno. All the politics. If your unseelie you have Andais to deal with, and though we have seen little of the light court I almost think that would be worse. Instead of being what they are, they are backstabbing and wrap up their inner darkness with beauty and light. And if you’re not of the courts, well… that would be pretty lonely.
Nabeshin! Woo! Yeah, that’d be up there on my list. Afro-power.
Hm. Kryptonian? That’s always a good one… especially pre-Crisis Kryptonian. Oh yeah. A Green Lantern would be cool, too.
Let’s see. Prince of Amber’s already been said, but I’ll second it.
A Familiar.
From Several Dara Joy’s Futuristic Romance Novels.
Failing that, I wouldn’t mind being Indiana Jones.
Oh wait, I just thought of something!!
6’2", 40DD’s, long dark hair …
ohmigod!!
'm WONDER WOMAN[/CENTER]
Whoo-hoo!!!
Yeepers, you folks like panic? Constant mortal danger??? I wouldn’t be Indiana Jones for all the tea in China!
I’m thinking maybe I’d like to be a Pei’an–one of the twenty-six Names that live.
Bonus points to anyone who can name that story/world!