First: the caveat. With the possible exception of spiny Barberries (Berberis) there are no absolutely deer-proof plants. If the herd is large enough, and food is scarce enough, deer have been known to eat almost anything.
There are plants that are much less palatable to deer, though even these "resistant" varieties are vulnerable in the first few weeks after planting when their leaf tissue is especially nitrogen-rich. If you have a deer problem in your neighborhood, it's a good idea to draw heavily from the group of plants you see below, all of which are rarely browsed. This list is drawn primarily from research done in New York, New Jersey, and Pennsylvania.
We've also had good luck with Deer Stopper® spray, available here.