Yup these work a treat, some kingchrome sockets have this, as do sidchrome spaners.
I had a few bolts that were rounded off and no spanner or socket in my collection could undo them (various cheapos, some good stuff as well) i went and bought a kingchrome socket and it worked a treat!
As long as the nut isn't circular, there is a type of spanner that goes on them, and instead of having the "sharp" corners, they are drilled out a bit, and it makes the "spanner" lock onto the nuts straights sides instead of the corners...
They work well...