Do not know is there any related subject so I'll create1

1. In game Auction House (You leave your item, set a minimum price and check from time to time is it already sold

2. Massive Wars like I saw in other mmo games (two side of conflict and 250+ vs 250+) They could be organized once or twice a week.
3. Individual character look (something like "My asura has longer ears than yours") age of characters which could influence to character's look.
4. Unique Items and unique upgrades. I mean real unique which can not be replaced with any pvp created item. At the moment in Guild Wars you can see running clones. I would like to have fully personalized character with only mine look and only mine items set.
5. Guild can own a city like in Factions at the moment. When player enters a town a message appear: “This city belongs to Hellfire Impact guild” Which must be defended by the guild (every Saturday at 6pm) 5-10% taxes from everything that is sold/buy in town will be given to the guild.
6. Personalization of guild hall – from a small village to a great castle.
7. Familiars and pets which you can ride on(horses, small flying dragons, running beasts)
Now it’s your turn :P