Lemon zest in large volumes
A Google search for "lemon zest machine" and "lemon zest machine commercial" found this and this. Both will surely zest faster than a hand zester, but probably will not zest 
better than a hand zester. The caveat of zesting a lot of fruit in house is that you will then have a lot of peeled fruit that you will also need to find a use for. This frequently works well for places making custards or fruit curds where they will need both the zest and juice. If only the zest is needed, it would be much easier to just get the zest from a produce company or frozen food supplier.