A few more, including NES
http://www.gp2x.de/cgi-bin/cfiles.cgi?0,0,0,0,23,1158
It's not really symbolic linking but I've been putting all games in a 'system' folder, all emus in the 'roms' folder and then creating a script to launch them in a '- Games -' or '- Emulators -' folder...