I feel your pain - we have 8 companies, and keeping straight where you are is a challenge. What I did is used “style filtering” (Options->Styling->Style Filter Manager) and created a style filter for each company.
Then, in Runtime Styler, I modified the background image of the TreeControlArea and uploaded country flags for each of our entities. The nice thing about modifying the TreeControlArea is that most screens propogate the control, so you can still see which country you’re in from SO Entry, etc.
