I've got a Logitech (cordless) keyboard with numerous extra keys on it.
I've found that a few of them work, those mapped to open the default e-mail and browser buttons for example. However, the best is that the four media keys, pause/play, stop, fwd and rev are all mappable.
I know have these in use, the pause/play is a natural enable/disable whilst the stop key (with a big square on it) acts as the centre key. The other two provide the final two TrackIR hot keys.
Very pleased...