A good website to check out (that's not just trying to sell gimmicks) is http://www.eagle-research.com/.
I don't work for them, I actually work for a different HHO company, but we don't post our research on the web, because we frankly don't have the time. Eagle research is a good place to go to read up on Brown's Gas and the applications for it.
If it's interesting enough to you, and you want to get into the HHO business, shoot me an email, we're setting up installers all over the country right now, we're just an HHO Generator Distributor (evolving into one over the next few weeks after we stop selling to the public)
HHO or Brown's Gas is made when you electolysize water. Go get a 9 volt battery, and wire the positive and negative terminals to two different nails. Get a cup of water and put a little baking soda into it. Drop in the nails, make sure they don't touch.
The bubbles that come off the nails are a Hydrogen/Oxygen mix, HHO, or Brown's Gas, when the conditions and consistencies are correctly measured out.
Make enough of that to fill a small balloon and you can blow up a nice loud H bomb for show and tell at school. (don't try to sue me if you blow off a finger though... it's powerful stuff and will replace all current gasses used in the welding industry before too long. Run on over to eagle research, you'll learn some really interesting stuff! It's an exciting topic that makes new headlines every day. Don't listen to the people who say it's voodoo. They haven't done the research, there's always naysayers for every great invention/innovation... Have a great day, best of luck to you
Drew
Andy@Rainingfuel.com