MMO missions...

...and that's another thing MMOs and RPGs could learn from the GTA games. Variety of missions.

Much of the gaming experience can be enhanced simply by providing your players with more options.

Hellgate's mini-game is a great example of this. Although the realism is somewhat fractured when the reward of completing a mini-game simply showers your character with items which have suddenly sprung into existence. I'd be tempted to have opened a portal into a treasure realm, perhaps the antithesis of the hell rifts, where useful equipment is lying around. For me this helps supports the notion that higher powers exist which are aiding and rewarding your heroism in the defeat of darkness.