I used to play another game - Insurgency - and some servers would append a prefix in front of player's names depending on where they're from. For example, [CN]cawfee. That wouldn't work on SA:MP, though, due to clan tags it would soon start to look messy. Just doing something like "cawfee[id] has connected from China" might be cool though.
Similarly, some people are very sensitive of their privacy and wouldn't like the thought of their Country being known to every man and his dog. We need to respect this.