I would very much like any and all MMO developers who are reading this to hear me: Please, please make your user interface as configurable as possible. Nothing frustrates me more when I come to a new game and find that I can’t resize or move UI elements to fit my preferences. I’m fussy that way.
I always thought that Cryptic did a good user interface. In City of Heroes and Star Trek Online, particularly, I was given free reign to get in there and tinker about until the UI felt usable and comfortable. It didn’t hurt none that those games’ UIs look sharp and aesthetically pleasing.
What options do you like in your MMO’s user interface? As an extra question, do you go the extra step of adding mods to further customize your UI?