Does he want MMO, lots of people and online community, like WOW, or both?
Xbox isn't known for its mmo games but there are some out there, most of them coming soon tbh.
As George mentioned, TES (Wow-ish, less cartoon like)
Kingdom Under Fire II (Wow-ish, less cartoon like)
Final fantasy (Wow-ish, some out and some coming)
Monster Hunter Frontier Online (only jp so far)
Champions Online (Hi-tech, old)
Stargate Worlds (Hi-tech and I think this may be canceled)
If single play is ok direct him towards..
Fable (maybe to linear)
Dragon Age (maybe to linear)
That exhausts my knowledge of xbox wow like games, good luck.
I know there are plenty of other fantasy setting games out there but most are linear single player experiences.
To err is human, to arr is pirate.