In the old forum we had the possibility of adding a tiny flag of any specific country. I used this in my signature, where I displayed both the Colombian and Argentinean flags. The flags were hosted at the following URLs:
Colombia:
http://forum.avsim.net/public/style_images/flags/co.png
Argentina:
http://forum.avsim.net/public/style_images/flags/ar.png
I guess that, for other countries, you had just to change the 2-letter country code at the end. As you may see in my signature, these flags are not available anymore. Can them be brought back?