well if you play a mmorpg nowadays you probably are either a die hard lone wolf or you joined a guild or clan. often mmorpg makers even encourage the forming of guilds, give them ingame means like clan housing, clanchannels and so forth but...
from a rpg point of view i think guilds/ clans make no sense at all !
- why would a rogue and a paladin join a common guild ?
- why would a darkelve and an elf be in 1 clan (and how do their parents look like) ?
what you should have is fellowships, companions that gather for a common cause, grow custom to adventure together and form some kind of friendship. but that would rather reflect groups and not huge organisations of 50 or more players.
keep the so called guilds/clans but call them taverns if you like and bring in gm controlled guilds/fractions for political power struggle and story developement
the guilds we have in most mmorpgs are 80% means of player organisation (guildboard for raids, sieges, a birthday calender for players, a chat where you talk about how your work day was and what movies rock atm). agreed there are a few rpg guilds out there but very few truly represent a classical guild as you would see in a historical setting or pen&paper rpg. most guilds resemble more a tavern where various people meet, some regular customers, some travelers to tell stories, socialize and sometimes have a common event.
a guild in the typical sense should have a firm storydriven place in the political struggle of your mmo world. look at the "league of assasins", "the order of the rose" or the "thieves guild of karatshi".
it makes a lot more sense if your character belongs to a guild because of his class or to a clan because of his race. the political struggle between the guilds or clans could be far more interesting and in synch with the overall game setting if a gm would be guildmaster then just a guy that grabs a ton of hardcore gamers to pwn the server. true there is a place in a games storyline where a charackter would gather a handfull of outcast to overthrow the king but atm it is just a shortcut for developers not to include/further content and let players run free on the server.
a team of gms on the other hand could realy orchestrate plot developement and intrigues in guild vs guild strugle that would deepen the rpg feeling in the mmo. i know that theres prolly not enough cash to pay real gms as actors but thats a topic for another blog to come...