Here's a useful suggestion that has its roots back in the old cheat program UOExtreme, but is actually useful for roleplaying:
A UO-translator, which allows users to assign short "keywords" to be translated into full phrases, which are displayed as the character's speech.
For example, you would make a keyword like "j1" or "xhail" and assign it to a translated text "Hail and well met, friend!" This way you would only need to type a short word which would be translated after you hit the enter key. You could make a whole list of these keyword/phrase combinations and be able to quickly say things without making macros for them. (for instance, "jban" -> "I ban thee!")
This worked in past versions of UO with UOE, but I'm not sure if it's possible anymore. I am sure that a lot of people would find it useful if it could be resurrected. I also can't think of a way that it could be used to cheat. If you need me to explain the concept further just ask.
Not a top priority, but I thought it might be a cool feature.