Not on Guitar Hero 3, but you can download songs for all of the other Guitar Hero games.
you can download songs online and insert it to your guitar hero game. search how to download songs to guitar hero two.
for the wii, through the shop channel... but you can't download old guitar hero songs into world tour
You download answers
You can't download songs.
no.. not at this time
no,but you CAN download songs and custom them for the Xbox 360
No, there is no DLC for Guitar Hero: Aerosmith on any of the systems it is on.