Has anyone documented what the keystrokes do? I'm experimenting with an el-cheapo "Micro Innovations" wireless keyboard/mouse combo connected to the usb port, some of the keys seem to correspond to remote buttons, it works good for the search feature and the mouse appears to work only in the guide. One downside I've noticed is that the 721 seems to get real sluggish and has spontaneously rebooted a couple of times.