What about something that allows a larger player to use up their resources, especially mcgrail. The castle system is really outdated, we all know that. I remember Helios was thinking of making player-run sort of 'cities' where you can build roads and buildings and kind of dedicate purposes for them, maybe like player run shops, inns, pubs, anything. It could have mobs patroling that could perhaps be programmed to disallow entry of certain people etc...

This could be an opportunity to increase the amount of player made content as well as a way to have people socialize and RP in a neat sort of way. If you're looking to increase HM perks, here would be another way as well, to limit this to people of a certain social status kind of the way it was in the old days.