Drill Bit Sharpener....

Not cheap and I don't use it all that much, but I scored an old Atlas "jig" that bolts to the bench, using a bench grinder. THEY ARE expensive if you can find one, unless you get lucky at some dusty garage sale

Article on them, as well as the cheaper jigs such as General

http://www.lathes.co.uk/atlas-drill-grinder/