I can reel off official hardware right now (not 100% on the names) capable of playing Hucards/CDs...
Turbografx 16
Turbo CD
Turbo Duo
Turbo Express
Laseractive/laseractive Hu interface
NEC monitor
PC engine*
CDROM2*
IFU-30*
RAU-30
Core Grafx
Core Grafx II
Super CDROM2
PC Engine LT
PC Engine GT
Dou
Duo R
Duo RX
PC engine Shuttle
Super Grafx
Super Grafx expansion stick massive thing
Then the pads:
White pad (original)
White Pad with turbo
Blue pad
Orange pad
shuttle pad
Avenue 6
Purple Pad
White/lilac pad
Duo RX 6 button pad
Avenue 3 pad
Blaster (3 button)
GT/Express TV tuner
(no knowledge of US pads)
Hori Commander
HOri.. small pad, like the famicom version
Several 2 button sticks in various colours
Mouse
AV booster
Ten no koe bank
rgghh, the other save bank that goes through the pad port
game cushion
Kareoke interface?
Shuttle save module
LT/Super CD bus expander
RF cable
Express/GT comm cable
replacement PSUs
Duo monitor
umm... brain... meltdown?
*Available seperately or together