My favorite organic molecule would have to be caffeine. Without caffeine, I`d have a lot of trouble doing anything with my day before noon. Caffeine makes many people, including myself, more productive individuals, benefiting society as a whole.
Archeological evidence suggests that humans have been using caffeine since before recorded history. Coffee, one of the most popular sources of caffeine, originated in ethiopia. According to legend, a goatherder observed his goats becoming energetic and restless at night after eating coffee beans. After he ate some of the coffee beans, he experienced similar effects ( http://www.scienceofcooking.com/caffeine.htm).
Caffeine is a naturally occurring compound, being present in many plant products such as tealeaves and coffee beans. Caffeine can also be synthesized artificially, which can be more cost effective than isolating the compound from a natural source. (http://www.wisegeek.org/what-are-natural-sources-of-caffeine.htm)
Caffeine functions by binding to, but not activating, adenosine receptors in the brain. This causes a decrease in adenosine, which in turn causes an increase in dopamine, creating a stimulant effect. (http://www.scienceofcooking.com/caffeine.htm)
The caffeine molecule has the formula C8H10N4O2 , includes 4 double bonds, and consists 2 connected rings of Carbon and Nitrogen, as shown in the model I created with chemdraw, based off of the image on this webpage (http://chem242.wikispaces.com/Sabina%27s+Analysis+of+HNMR+of+Caffeine). I chose to use a skeletal structure, omitting the Hydrogen and Carbon for simplicity.