This kind of gives a light show effect. Sorta, I mean, it's not exactly a Kanye style light show, but it does throw pretty patterns onto the wall and ceiling and it's dead easy to make.
I think I've covered the basics here, but if you get stuck (or you're looking for some other ideas on Dirt Cheap Decorating) go here

Step 1: Gather Your Stuff

I used:
a Grundtal lamp base from Ikea
a Skimra lamp shade from Ikea
craft paper
scissor
a craft knife
tape
pencil

Step 2: Figure Out the Area You Have to Work With

Draw 'round your lamp shade, to figure out it's surface area.

Step 3: Plot Out Then Cut Out Your Design

Bear in mind that you won't be cutting out the whole outline of your design, just peeling up the edges.

Step 4: Pinch Out Your Edges

Pop the template over the lamp shade and secure it with a bit of tape. Then peel and pinch out the edges of your design, this will let you see how it's going to look.

Step 5: Plot Out Then Cut Out Your Design... Again

This time you'll be marking out your design onto the actual lampshade, using a pencil and your pre-cut outlines as a guide. Once that's done, carefully cut out your design using a craft knife.

Step 6: Pinch Out Yor Edges... Again

This is slightly harder than it is with the paper template. Clean hands and patience come in useful here.
Also try folding your edges back a few degrees at a time rather than jamming them back all the way in one go.