Here is a tutorial on how to build a 4 channels wireless remote control for you Canon EOS camera.
The total cost of this project is around $50.
All needed materials can easily be found at ebay and radioshack
Here is a nice little trick I found on a web forum about how you can get free coloured gel filters for you Canon (and probably other brands) flashguns.
Today I was feeling like getting my hands dirty, so I went on surfing the net for some Do It Yourself (DIY) projects, and instead of just one I found 2 very promising projects