A boxing trainer I used to go to used something called "Virtual Knockout." It was like hitting focus mitts but the thing would hit back at you and you'd have to block or slip. It was pretty cool.
http://www.ajmshopping.co.uk/more_details.asp?ItemCode=02203
Also, Ringside sells a heavy bag attachment called "The Opponent." It bounces off the bag when you hit it, and you have to slip it.
http://www.ringside.com/DETAIL.ASPX?ID=24747
Or, if you want, they're not all that great, but better than nothing: they sell those TV games where you put on the gloves and it tracks your movement while you box a virtual opponent. The ones in arcades are way better; they're 3D, good graphics, have weighted gloves, and count how many calories you burn. These ones aren't as high quality, but you could always throw some weights on your hands and it's still that much better than shadowboxing.
http://www.fuzing.com/vli/000122c3a2...Boxing_TV_Game
Again, the 3D one is way better.
Best training device that hits you: a partner
Use your imagination when you're shadowboxing and hitting the bag though. Always be thinking about an alive, resisting opponent, and work with that. You're only limited by your imagination and desire to train.
