There are so many things, that while not implemented specifically by the developer, have come about through people's work and thought, I think it'd be cool to list them all, just to see them, and to give the devs a moral boost for making an awesome game. These are what I can think of (in no specific order), any suggestions to be added are highly encouraged:
Towns (though in the future this may have to come off the list, there are currently no things that specifically specify towns)
Communism
Trade
Road systems
Vaults
Mail system (it's being worked on...)
Hired/Volunteer Rangers/"Law" keepers
Graves
Stockpiles
Revenge
Wandering Rune Carvers
Inns
Explorers
Shrines