Give guilds the ability to purchase a hall/house on one of the outposts. Members could then decorate it with their various trophies/trinkets, the building could be upgraded depending on guild rank to offer storage of certain items, more hooks (trophies, trinkets etc) and other social cosmetics. Entry could be instanced like the hideouts, as in go up to the door unlock it and enter. Guild leaders could set permissions for decorating to prevent abuse, halls could even be made public to enable non members to visit. There's lots of options, I feel it would expand upon the guild theme in game.
