My mom made the simplest advent calendar ever, and I wanted one each year! It takes five minutes to make and looks great!
But you have to approve of chocolate. Hard, I know.
Cut a basic Xmas tree shape out of cardboard and cover it with green foil wrapping paper. (Cheap and easy version: a simple tall triangle from green tagboard or even construction paper.) You can re-use this if you're careful, or you can recycle it each year.
Get 24 Hershey's kisses in red, green, and silver. (Deluxe version: get the almond ones, they come in gold as well.)
Glue them on the tree shape like ornaments. (You could decorate it with other objects as well, but I never felt it necessary. Because CHOCOLATE!)
Unwrap and eat one every night, ending on Xmas Eve. (Peel the foil back, pick out the kiss, then mash the foil back down into a flat disc so it still looks like an ornament.)
Now go brush your teeth and jump into bed!