Here are a few very simple Christmas activities that take only a few materials to make. You may know them, but I find that I forget to do them until my kids remind me of how fun they can be!
Candy Cane Christmas Ornaments
All that is needed for this one is red or white pipe cleaners and red and white pony beads.

You just string the beads on the pipe cleaners and bend up each of the ends to hold the beads on.

Bend it into the shape of a candy cane and slip onto the Christmas tree.
Chocolate Spoons 
This needs plastic spoons, chocolate chips (or Wilton melting chips), and decorating sugar and/or pieces. It can only be done with children old enough to understand how to be safe with hot melted chocolate.

Melt the chocolate chips in the microwave or on the stove and bring to the table. Have them dip the spoons in and then add decorations. Place on a piece of wax paper. Refrigerate for about 15 minutes, until hardened. These are great in hot chocolate or coffee, or to give as gifts (especially with a jar of hot cocoa mix.)
Ice Cream Cone Christmas Trees 
These require sugar ice cream cones, white frosting tinted green, various candies for decorations.

Just turn the cone upside down on a plate, and frost with the icing.

Decorate with whatever candies you have on hand or wish to use.

Use as decorations (especially nice for gingerbread house scenes) or eat as a treat!
Holiday S'mores
This is just like making regular S'mores (graham cracker, chocolate squares, marshmallows and another graham cracker) but you use holiday Peeps (snowmen, in this case) for the marshmallows and just microwave for about 10 seconds.
Have you ever watched Peeps in the microwave? They puff up wonderfully. The boys love to watch them.
The ingredients in a small gift bag (my kids received these as take-home bags at a dance) would also make a nice addition to a food gift basket.