Originally, this was part of a blog I'm writing concerning group gameplay versus individual gameplay. But it's become so long, I'm going to make this its own article.
FOR LOOT OR NOBLE REWARD
The Three Amigos faced El Guapo to save the town, not to rob the thieves.
Current MMOs are more encouraging of mercenary alliances of convenience than of noble causes. In real life, individuals are often filled with a powerful sense of self-satisfaction when they recall memories of good deeds he or she has done, or when the deed's recipient smiles back appreciatively. If noble action can be so fulfilling in reality, then it could certainly be fulfilling in a game as well. There's a significant affectual difference between helping another person and helping an NPC, but each can be gratifying.
Sure, games regularly offer players opportunities for noble deeds, but there is always another form of reward (and usually not just one) that often seems to overshadow the player's good will. It might be only experience points, or loot, or faction that can be "cashed in" for something beside good favor. As I'm sure I've written somewhere before, I'd like to see rewards more separated: loot alone, xp alone, faction alone... and nobility alone.
Players could join organizations for the expressed purpose of noble deeds, perhaps even of a particular scope. And the appeal isn't limited to roleplay (enter the "virtual world vs game" debate =P ). These can be fun.
Those paladin pansies...
For example, a paladin might occasionally group with fellows of his order to keep an enemy population in check. In the upcoming MMO Darkfall, a dynamic spawning system allows a creature population to "migrate" after being overhunted in one area. Such a setting would be ideal for this sort of organization.
The paladin order could not only maintain safety on one particular border, but they might also perform reconaissance and travel from one area to the next hunting zombies or demonspawn. If developers allowed these creature populations to grow to burdensome levels if left unchecked, then player paladins might even receive encouragement from non-paladins! In this case, though there may be many types of rewards involved in the struggle at any given time, it is clear how such a system may keep an impression of noble action front-and-center.
Herbs on demand
Another possibility is an alchemical organization driven by NPC groups with alchemical needs. In fact, this provides a way to show how one altruistic organization might be bound to another.
Suppose that the undead, which the paladins attempt to keep in check, can have some negative effect on NPC villages that they come into contact with. The effect might be perpetual fear, illness, or might even be a plethora of maladies. The alchemical organization would then enter the village to obtain, create, and apply remedies (with visually perceptible effects) to the NPC population.
The paladin order might often be the messenger of need, calling upon the alchemical society after raids; or vis versa. There might even be circumstances in which the two organizations must work cooperatively for success. For instance, a stricken village might be extremely hard to cure as long as undead just outside its borders exert a psychic hold over the villagers (i.e., undead leaders must be slain to release the town from corruption). Or (in the opposite direction) the paladins might call on the alchemists to purify a holy pool which is a boon to paladin powers in the area, thereby strengthening the paladins against nearby undead.
In short, it is feasible for altruism to be its own reward at times in games (within the context of enjoying the act itself...like combat). It isn't necessary for grouping with other players to always involve a possibility of personal gain. Sometimes enjoyment come from feeling helpful and identifying one's self with a larger and nobler cause.