Nice one, I'll bear it in mind next time I have to do some bodywork. I have a detail sander which I think is very similar, just a bit more bulky. The other tool I have that is also very useful is a powerfile. Don't know too may people that have bought one but they are excellent for reomoving large corrosion deposits in confined spaces.
Fortunately haven't had to use either on my current cars, at least not yet.