The user-interfaces and feature-sets of a lot of MMOGs (and most particularly the big ticket games) tend to be a bit homogenous these days. Why shouldn't they be, after all? Developers want to both emulate success by emulating what is already working, and to reduce the learning curve by giving you familiar interfaces and mechanics.
Massively thinks that's both a good thing and a bad thing. It's almost like innovation is being punished, but -- heck -- they're all still having a good time, right? Still, while the substrate is a bit homogenous, everyone tries to get at least one or two distinctive features into their game. What's the best feature you've seen in an MMO -- something you wish other MMOGs had, or just something stand-out cool?