No, these aren’t instructions on how to build a fully controlable, fully functional remote control hovercraft.  But these are instructions on how to make a small, cheap, fun hovercraft out of an old cd, some super glue, a balloon, and the top to an old water bottle.  The only hard part I saw with these instructions is how to blow up the balloon once its atatched to the cd…….

http://www.techeblog.com/index.php/tech-gadget/video-make-a-mini-hovercraft 

If that’s not your thing, heres another short vid on how to have some fun with a small amount of dry ice.  Add a little water, and you’ve got smoke.  Add some soapy water, and you’ve got very cool (literally) bubbles.  Just as a quick safety warning, if you actually try this, dry ice is very very cold, so be careful.  Burns and/or frostbite just aren’t fun.

http://www.metacafe.com/watch/286601/dry_ice/