Roger Zalazny's Amber series
Lawrence Watt-Evan's Ethshar series, starting with
The Misenchanted Sword
Does he like Dragons/Fantasy? If so, I've just read Jo Walton's
Tooth and Claw which I really liked. But it's not your usual Dragon fantasy story....
How about
Kidnapped by Robert Louis Stevenson as an adventuresome classic? The book is much better than the films.
Scott Martin's
Thraxas series is an excellent detective fantasy (although sadly incomplete)
John Ringo's short series that starts with
March Upcountry is very good
Terry Pratchett's Johhny Maxwell series, starting with
Only You Can Save Mankind.
OK, that's half the alphabet covered.
