Ok lets talk about the Monk character class. I personally can't see myself allowing them in a campaign I am running unless there is some sort of oriental connection, or some sort of all monk campaign where all the characters and NPCs are monks, perhaps like a Kung-Fu movie with a Karate Kid climax. That being said I'll usually allow almost anything the players can justify with an exceptional background story and/or character motivation.
I really think the problem here is that the monk is not developed enough. We know he/she belongs to some temple (probably) but there has never been any kind of development on what temples are like for the monk. Do they worship a deity or some kind of alignment abstraction (or divine concept as explained in the Pathfinder Core Rulebook under clerics - such as battle, death, justice, knowledge). Are monks' temples the same as clerics' temples? Do they worship the same gods or divine concepts? In the Pathfinder Advanced Players Guide one thing I found promising about this class is the inclusion of different class features manifesting themselves as monk philosophies such as Drunken Master, Hungry Ghost Hand, Ki Mystic etc. This is a great start as it can provide motivation and story background. I can just see a monk NPC showing up just as the party is about to achieve success and throw a wrench in things because he is from a temple of an opposed philosophy.
In general I tend to agree with the AD&D oriental adventures book that the monk does not belong with the western style character classes and is better suited to an oriental campaign. If one is to include the monk in the west in any AD&D FRPG offspring game or have an oriental campaign for that matter then there should also be a set of oriental classes.
Pathfinder could use class archetypes that modify the traditional classes such as fighter/ranger - bushi, rogue-yakuza, cleric-sohei/shukenja, palladin-samurai, cavalier-kensai, wizard/sorcerer-wu-jen and prestige classes such as assassin-ninja.
Castles & Crusades should be even easier with fighter/ranger-bushi, rogue-yakusa, assassin-ninja, monk and barbarian stay the same, wizard/illusionist- wu-jen, cleric/druid-sohei/shukenja, knight/paladin-samurai. Just invent some oriental class abilities that better reflect the oriental flavour of the character. I personally think this is what was intended in the first place and why the monk was included as it was not like wu-jen being just a magic-user by another name, but something with no western unarmed martial-master counterpart.
I think if the monk is to really shine as a character class much of the above needs to be resolved, either by game publishers, or even better, by imaginative referees.