My favorite human organ is the brain.
And considering that an organ is totally a thing (reference, The Anatomy of Things), I made a screen-printed plaque to honor the brain, with all of the major lobes labeled!
I am officially a nerd.
If you share my brain obsession, it would be very wrong if you have not heard VS Ramachandran speak about the brain's influence on civilization (mirror neurons) and his experience with various brain syndromes and what they teach us about the brain (Capgras Syndrome, phantom limbs, and synesthesia). So cool. Watch them at TED.com, a super sweet website full of lectures about all sorts of interesting topics.
What is your favorite organ, and why?