Get him a copy of World of Warcraft and maybe a cute girl's phone number.
I used to play FFXI and I can pretty much confirm 100% of what the second poster said.
Really the only nice thing he can get at the point of having multiple level 75 jobs is that either he can get a really nice item that takes an alliance and hours to obtain, or get him something to get him away from that cursed game.
Seriously Final Fantasy XI is more like a peep show that gets more expensive everytime you go to see your favorite girl, and you get to see less and less with promises of getting more than what you wanted in the first place.
It's pretty much a downward spiral game that eventually leads to you losing your real life companions and hobbies like a girlfriend, friends, goals in life.
I played FFXI through to 75 as a paladin, did the whole end-game thing. It was just too overwhelming when people tried to explain it to me. "Well join a linkshell, start hunting mats for summons and after about a month or two months of farming mats to summon gods, you go and fight gods and earn DKP toward getting your first abjuration in maybe 4-6 months."
Wait... 4-6 months just for ONE piece of equipment? Oooookay... How's this World of Warcraft game over here? Played that, the format was the same, only it was more fast paced. (Get to max level fast, get epic equipment fast, only the equipment becomes outdated fast as well, the illusion of fast = easier to complete is held strong by Blizzard)
Want to get him a nice gift? Buy him Final Fantasy XII. It has all the things most people love about Final Fantasy XI, only none of the faults. (I.E - Same grind and get powerful gameplay scheme, active battle system gives the MMORPG feel to it, hard to get items that take hours of grinding to obtain, over 50 hours of sidequests and optional bosses, but none of the faults of Final Fantasy XI, i.e - Dependance of others to accomplish anything, tediousness of competing with other players for certain items, ingame economy that is so unstable, you're suprised FFXI players haven't commit suicide because of a "digital stock market" crash)
Yeah, I'm a bit of a ranter about FFXI, but long story short- Get him something else, get him away from that cursed game.
You could throw Carmen Electra with Santa's Helper lingerie into a box and give that to him for Christmas, and he'd still be thinking, "Man I'd kill for an eastern abjuration and a cursed -1 item right now."