Mandolines are the secret behind super-thin and extraordinarily even slicing. They have a flat surface with a razor-sharp blade that can be adjusted to cut thicker and thinner slices. High-end mandolines come with attachments to make julienne cuts or shreds, wavy-cuts, and even waffle-cuts. The simplest models don't adjust, but just slice very thinly.
Mandolines are so good at slicing because they have such a sharp surface. Most models come with some type of holder to keep your hand away from the blade. Many professional cooks choose to wear metal mesh gloves when using mandolines to protect their fingers and hands. Extreme caution should always be observed when using any mandoline.
There are many fine mandolines on the market, from heavy metal adjustable French constructions to smaller, lighter, and much cheaper single-slice plastic options that many cooks swear by. My favorite is the OXO Mandoline Slicer. It's as strong and durable as the old-school metal French mandolines, the thickness of the cut is easily and safely adjustable with a knob to move the super-sharp blade up and down, and that same knob simply flips up the different julienne blades (unlike more tradition models that require you to actually lift out and change the blades, risking fingers every time!). Plus, the stand folds down for easy storage, the handle to hold food for safe slicing works with pretty much anything you'd want to slice, and it cleans up with ease.