What link? *feels like he missed something*
On topic:
I like rituals in different contexts.
- some sort of "megabuff" during/before fights like in EQ II
- as "key" for special dungeons/tribe treasures
- quests/events (multiplayer mostly, but also sp)
- recurring race/religion-specific events (similar to xmas)
- recurring political/social events, there are also guild-specific quests and events