DS - flashcard (G6DS Real)... not sure if that's concidered a mod, since there are no real mods for the DS
XBox - Softmod - XBMC with OEM Hard Drive, and networked 500gig drive
Sega Saturn - triple switch for region selection, but still doing swap trick
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Had
PS2 with a chip that I can't remember what it was, lol
GameCube with a chip I can't remember
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Getting
WiiKey for my Wii soon