Here's a quick pop-up that only takes a few minutes and has a nice effect. All you need is a printer (preferably color) and something to cut with.
Original design by Masahiro Chatani.
Step 1: Print Out This File
Step 2: Cut Along the Black Lines
My preference is for an Xacto, but whatever works for you.
Step 3: Blue Valleys and Red Mountains
Fold in along the blue lines and out along the red lines so that you have blue valleys and red mountains.
Step 4: Enjoy the Pattern
Make sure that the folds are nice and clean. When you're all done you should be able to flatten it in on itself to make the folds more solid.
Now carefully stand it up and enjoy the zigzagging pieces of paper.