Somebody with a broken clutch cable just called me.  He's about an hour from home and the clutch cable broke at the lever.  

Anybody got any good suggestions on how it might be possible to limp home?

Tie a good strong string around the clutch lever at the transmission and try and pull it forward as needed?  Probably as dangerous as hell but maybe preferable to pushing the bike.

Hope he didn't lose the cable pivot, which will likely need a good greasing.

Replacing the cable is preferable, but in an EMERGENCY situation once going clutchless gear changes are possible. The hard bit is the start, place the bike in 2nd gear and hit the starter button and as it fires up gently accelerate. The start can be jerky and you could loose your balance you need to be smooth with the accelerator otherwise it could be disastrous if you give it too much gas. Alternatively rolling down a hill and pushing it into second gear while accelerating gently is easier, but hills tend to be absent when needed. Stops are a case of braking and changing down gears (optional) and placing the bike in neutral. I would not try this in traffic. The idea is to get to a place where you can wait safely while help arrives. Riding without a clutch can be dangerous if care is not taken, you need to think ahead and plan your stops.
Regards Martin.