One thing which I cannot do myself is "making the GUI pretty" -- I know how to work with a C++ code and can manage the QML code most of the time, but I'm certainly not a designer.

Another thing which is missing from the Touch UI is support for actually rendering messages. If you'd like to add that, go ahead, but I hope I'll find some time to add that.

Another things are bits like menu for controlling offline/online mode, integrating with the gconf backend for storing user's preferences, maybe moving them to the Settings app. etc etc.