What do you use to get even uniform potato slices, for let's say, au gratin? But this would apply to anything that requires uniform slices: apples, plums, carrots etc.
Food processor, mandoline or just slice by hand with a good chef's knife.
(Yes, this is an offshoot from my previous post of whether people use their food processors, and whether there was a compelling reason for me to get one. What can I say? After I decided to NOT to, they lowered the price yet again.)