I found this fun site that has some cool sciency like home projects.
http://www.scitoys.com/scitoys/scito.../electro6.html
The one I found the best, a Van de Graaff Generator!
What is a Van de Graaff generator you ask? Well, basically, it is a static emitting device, that can be used to power lightbulbs, raise hair, or just to have some fun and shocking yourself (don't ramp them up to high, one of our mentor's friends built one, he cranked up the power, and touched it. He woke up 3 hours later across the room).
You can buy one of these, a bit larger for around $500, but why buy something that you can build!
I built one, but it only works when it feels like it (in otherwords, it's not that great)
It's only my first, but my second will probably be better.
These plans will only run you $15 to $25 (but this can increase if you plan on using an actual steel ball that you have to special order (this site just tells you to use a pop can)
This only ran me around $15, but that's because I already had the motor for it.
So, whacha think?