Ever wonder how lava lamps work?  
Um, no... me, either. Still, the information is out there, thanks to the folks at How Stuff Works. Check it out -- it's a complete guide to the history, physics, and even how to make your own!  
So if you're an unapologetic hippie throwback -- or you'd just like to be -- have a look. Soon, you'll be saying, 'Ooooooh' just like it was 1972. Duuuude!