Here is a really cute snack that my kindergarten students loved making. These ingredients can be modified due to allergies or preferences. I second the finger food trays...my kids have always loved the shaped cheeses.
whole wheat bread
red apple slices
You can precut the bread and make a sample because these are simple for the kids to make and they disappear fast.
Cut the bread into triangles(1/2 for 1 large reindeer or 1/4 for 2 small ones.) Spread peanut butter on two of the triangles. Decorate with raisins for eyes, a slice of red apple for the mouth, a m&m for the nose, and pretzels for the antlers.
Icing colored green with food coloring
M&M's, gumdrops, raisins, string licorice any small treats to decorate the tree.
Take one cone and spread the icing on it. Place the cone on a plate point side up and allow kids to decorate with the treats. Enjoy!
I've always found really neat ideas at http://familyfun.go.com/ if you need others.