These include flags for countries, states (US, UK, UAE, Australia, Belgium, Canada, Holland, & Spain), organizations, and signal flags.
All total there's about 428 flags.
Now I seriously doubt we need all of those so I'll put it to y'all to decide what you want.
My thoughts are, whoever wants to use one of these flags as their avatar just let me know and I'll add it to the avatar folder for ya'.
Bear in mind there may soon be coming a set of railroad logos that can be used as avatars also.
Edit 1: As you can see, there's also the option of adding a flag to your sig as seen in Redband's posts.