The panel in the upper-right corner (player / faction ranking ?) can't be hidden (AFAIK). Personally I have no use for it, and would like to dismiss it. Any key combo that would hide it then pop it back up...
EDITED: I was more excited about this until I realized that my GUI was running at 130% (maybe the default?). Once I set it to 100% this was much less of an issue. But the request stands and is probably simple to add.
