The Audiophiliac's primary mission is turning readers on to high-quality audio products and great music, but today, it's more about super lo-fi.
Google's YouTube has loads of wacky videos on how to make cheap speakers. Check out my favorite so far, "How to Create a High-Def Speaker for Under a Buck," right. It doesn't work, but it's the most entertaining.
After that, watch "Attempting to Make a Homemade Speaker for Under a Buck." It's a response to that first one.
If you really want to give speaker building a try, go to Jose Pino's "How To Make a Speaker" page. His step-by-step instructions look more promising.
No, I didn't actually try to build any of these things, but Pino's project looks as if it would work.