Title explains the idea, I think that having a custom flag would be pretty cool. Instead of having my flag show USA I would have the dragon from skyrim, it would most likely be simple and the staff can make a system where you have to supply the picture and a set amount of tc (it's not like they are going to do this for free.) It's not something that makes a big change to the game so I doubt many people will have problems with it.

TL; DR
Change the flag you see next to your name to something custom
Adds silly little perk that does nothing but obviously is pretty cool
Sinks tc!