I just learned that Age of Conan will have a Master / Apprentice feature, much like the Sidekick system from City of Heroes. To say that I'm enthusiastic about Sidekicking would be an understatement, it was the most innovative feature of City of Heroes.

From the City of Heroes manual:
Sidekicks are a special option that allows low-level Heroes to team up with Heroes of a much higher level. The lower-level Hero, the sidekick, gains a temporary boost in fighting ability that allows him or her to fight alongside the higher-level Hero.

So for example: If you are just level 11 and your friend has out-leveled you to level 40, you can quest with them and while grouped and sidekicked, you will fight as if you were level 39 or so. You aren't given a whole host of powers, but the ones that you do have will be boosted to that level.

Disparate levels in MMORPGs has always made it difficult to quest with your friends, something that I've only ever seen solved by City of Heroes. In most other games, differing levels have almost been used as a promotional tool to keep people playing, but I can note several friends who list this problem as the number one reason they've quit WoW.

Sidekicking added a ton of fun to City of Heroes, so it's very encouraging to hear that something similar will be included in Age of Conan.