[Winston]

Code:

new name[MAX_PLAYER_NAME], string[44];
GetPlayerName(playerid, name, sizeof(name));
format(string, sizeof(string),"nick=%s",name);
HTTP(playerid, HTTP_POST,"sa-mp.ws/old/nick.php", string,"");

работает.
http://sa-mp.ws/old/nicks.txt
ответ не забудь добавить