RockMonkey
Suddenly Enthusiastic
Sheet metal hole cutters are sweet too!
http://vansantent.com/sheet_metal_cutters.htm
About $200 for the set that makes sense. I didn't see it on the page, but I assume that they are capable of making holes in 1/4" metal. The page only says "Their 1/4" depth of cut keeps vibration and distortion to a minimum." I guess I don't really have any problems with regular hole saws. They last me a long time, and make holes.