VIDEOPAC: the chess module
Master system: 1 extra controller
Megadrive: 3 extra controllers (1 with 6-buttons), a multitap
Super Nintendo: Super Scope, multitap, 4 extra controllers, 1 big arcade controller, Super Gameboy, Mario Paint mouse (I don't have it yet, but it should come in the mail pretty soon)
Nintendo 64: 3 extra controllers, one rumble pack
Dreamcast: 3 extra controllers, 1 gun, 4 rumble packs, 5 VMU
Gamecube: 3 extra controllers (1 Wavebird), 4 DK Bongos, 1 dance pad controller, Gameboy Player, Ethernet adapter, a nice bunch of memory cards, one GBA-GC cable
Wii: 3 extra wiimotes, 3 extra nunchuks, 1 Wii Zapper, 1 balance board, 1 dance pad controller, 1 guitar controller, 1 Wii Wheel, 1 Classic controller
PS2: 1 extra controller, 2 memory cards, 2 PS memory cards, 1 EyeToy camera
Gameboy: two rechargeable batteries (+charger), 1 loop+light, one link cable
Gameboy Advance: two wireless thingy, one 4-player cable, 2 rechargeable batteries (+charger), a carrying bag, around 8 small game cases
Nintendo DS: 2 car adapters, 3 DSLite stylus, 2 extendible stylus, some screen protectors, 10 small game cases