I have always wondered how people replace broken spokes on the rear drive side. For most wheels you would have to remove the cassette. I have a tool that will remove the cassette without a chain whip, but what are the other options?
I have not used it in the field but I have tried it out and it works well. It has been in my emergency bag for years and I hope not to have to use it, but you never know.
Here's mine, had it for about 15 years. Works fine (can be fiddly to fit in place) but I did put a dint in an aluminium chainstay with it once so I now put something under it to spread the load. Never had to use it in the wilds apart from tightening spokes. 37.5g on my cheapo scales. 2012_0525tool0001 by youngray50, on Flickr