Was looking around on dextrose the other day and found a post about using the broadband adapter with Phantasy Star Online to load code on the GC. Apparently since that game downloads a lot of quests and other stuff from the servers Sega might have just made it download executable files sometimes. If this is true it would open up the possibility of intercepting the connection and loading homebrew code onto the console. I've never played PSO though so I don't know anything about the protocol. Anyone who does play PSO online care to comment? Do the quests make any huge changes to the game/take a while to download?
Just an idea, since the GC homebrew scene is practically nonexistent right now