Build a Magnetic Ball Levitator for $20
“There’s a super article in Popular Electronics, May 1996, pp 48-52, 78, titled “Build a Magnetic Ball Levitator”, by James Cicon. It describes how to build an electromagnet with an optical sensor which will keep a hollow steel ball floating in the air about 1/4″ below the electromagnet. This is like the globe of the earth which is suspended in air under an electromagnet that can be purchased for about $125. The material costs for this project is only about $20.” Link.
Wow, this will likely be commonplace in just a few years…“Build a low-cost, terabyte-sized backup server using Linux and back up your digital audio files, digital images and digital movie recordings. A terabyte-plus backup and storage system is now an affordable option for Linux users. This article discusses options for building and configuring an inexpensive, expandable, Linux-based backup server.” 
“What you see before you is an OPEN DSP system. People are currently using it to create some of the most ORIGINAL-SOUNDING EFFECTS and INSTRUMENTS in the world, since its architecture is open. Its users tweak, modify, CUSTOMIZE, improve and develop the software it comes with. It’s inexpensive and can be quite portable. It runs MIDI or connects to your Palm Pilot. Some programs don’t require either to make fun and useful effects.” [
Bill writes “When I saw the retro-phone handset on thinkgeek I knew I wanted one. Then I realized they wanted $30+ for it, and I thought to myself — I can build that. So after some cutting, testing, and building I have finished my Retro-Cell phone handset, and I will show you how you can build your own for under $10.00″ 
Here’s how to make your own Canon Digital Rebel XT remote. “Instead of paying $20+ for a fragile remote on a short cable that has less features, I picked up about $10 in parts from Fry’s.” The article has a link to a how-to PDF and example photos. 
John writes “When I first saw the Dakota disposable cameras at a locals camera store I knew I’d be buying a few so I could make a camera that only exists in my dreams, a digital stereo camera. After seeing the Use the (PureDigital) Dakota Digital Camera with your PC, I ran out and bought a few of these $11 dollar gems and set to work hacking them up. I figured I’d write up how I did it in case anyone else wants to try it themselves. It’s a pretty easy hack all things told, but still darn cool.” 
Obeyken writes “Electronic / kinetic bug art. I build these small, insect-like sculptures with simple motion-detecting “antennae” that respond to various stimulus such as movement, vibration, or air currents. When picked up, handled, or otherwise stimulated, the bug comes to life as its LED eyes blink rhythmically. I have one sitting on my monitor right now that blinks as I type. They’re constructed from LEDs, bits of wire, guitar strings, and coin-cell batteries (the PCB battery holder is the bug’s “body”). My original plan was to deploy them throughout San Francisco as a sort of “electronic graffiti” but thus far they haven’t survived too long in the wild…” 