I would really love to see a system in FFXIV akin to Public Quests from Warhammer. Public Quests are area-specific, ongoing quests that are automatically assigned to each player that enters the area. All players work toward completing that same quest, if they choose to participate.
Public Quests typically involve several (most commonly 3) stages and conclude with a large fight against one or more Hero tier opponents. When a public quest is completed, each player who participated will receive a reward based on his contribution to the whole.
I found PQ's to be the most innovative, fun, and rewarding aspect of WAR and would love to see SE copy it. What does everyone else think?