I've been thinking, and having quests dedicated to a specific class or character type would be good. What i mean is that having a quest for a silent , quick assassin to dispatch a fat, greedy richman, or a job for a mage to search for a book in the library that has magical properties. I think that this kind of quest could be done ONCE in a chars lifetime, once you've done the quest, you can ask the same person to do another, similar one. This could end in the end with you recieving a place in a faction, or a unique, magic item, along with some exp. This does remind me of dm quests though.

Some thought has already been put into this matter.

You may or may not see class specific quests appear in game. They won't be many though as it does not promote PC interaction (unless of course, any class can take it, but it's almost essential to bring a certain class to successfully complete it).