The Language file (which holds all the game's text strings) should hold more, particularily the version (very handy for times like in military, since its logo replaces the glest logo, but military isn't version 0.3....). As well, there's at least a few other strings that don't have a string in the language file, off the top of my head, I know one with the word "IP" in it on the join game menu isn't, since I tried to capitalize the word "IP" (Ip looks bad) but found it wasn't in the language file...
As well, another interesting thing might be the ability to add line breaks (\n) in the language files, such as, we might have the part of the intro screen which has the link to the Glest site, and we may change it to say "
www.glest.org\nwww.yoursite.com", etc;
The second idea is a bit more complex (maybe?) but the first is very much doable and would be beneficial.