Integrating LUA into Xlobby (as it is in Girder) would be the biggest single enabler for new capabilities that I could imagine.
With LUA integration, many folks that require Girder in addition to Xlobby to handle their needs might be able to meet those needs entirely within Xlobby.
If you have LUA, you have pretty much everything on your system available to you, without having to write individual plugins , since LUA can talk to COM objects.
A Script Event is what I would envision as a start, as well as a way to access LUA variables when designing a screen.
What do you say, Steve?