Nepetalactone - Kitty in the sky with diamonds

• psychedelic present in catnip (Nepeta cataria) that causes cats to party hearty (sniffing, rolling around, rubbing their chin against things, etc.)
• can be extracted from the plant using steam distillation
  
• unusual since most psychotropic drugs (those that act on the brain) affect a wide variety of mammalian species (this drug only appreciably affects cats)
  
• causes a mild buzz in humans
  
• only works by inhalation, feeding cats the plant in an encapsulated form (as a pill) produces no effect
• is a terpenoid, a class of aromatic (as in they have a scent, not a benzene ring) chemicals that include menthol, camphor and the cannabinoids (THC baby!)
• insect repellent and aphid sex pheromone (besides the inherent awesomeness of this, it also enables the drug to be used to promote the spread of aphid diseases as a green alternative to using insecticides)

Perrine, Daniel M. The chemistry of mind-altering drugs: history, pharmacology, and cultural context. Washington, DC: American Chemical Society, 1996.