Alright so I picked a pretty obvious organic molecule to love, and I know I'm not the only one to love it. My personal favorite is Theobromine, the main organic molecule in chocolate. To give you an idea of just how great this molecule is, it's very names derives from the Latin "Theobroma" meaning "food of the gods". There you have it. Right off the bat this molecule was given the credit it deserved. In fact, the more Theobromine a chocolate has, the higher it's quality is. Oh, and for the record, dark chocolate generally has more than milk chocolate (granted I still think milk chocolate tastes better). However, the amount of Theobromine in a cocoa bean can greatly vary, ranging from 300 to 1200 mg/ounce. This molecule is closely related to caffeine (another one of my favorites). It has a similar affect on humans as caffeine, but on a much smaller scale (unless you're like one of my friends who abstains from chocolate and caffeine so when she does eat it she goes crazy).
Anyhow, Theobromine is actually a type of Methylxanthine, a special class of alkaloid molecules that are found in over sixty plant species. I mentioned caffeine earlier being a close relative of this molecule and, yes, caffeine is in this group of alkaloids as well. Theobromine is the most important methylxanthine found in the cocoa tree, hence my reference to chocolate (and coffee for that matter!). As far as its use as a drug, Theobromine can be used as a mild stimulant and to relax the heart, as a treatment for high blood pressure due to its ability to shrink blood vessels, and also to increase urine production as well as be found in cough medicines.
Lastly, I would like to thank the Russian chemist, Alexander Woskresensky, for discovering this fantastic molecule that gives me and so many others so much joy. He discovered Theobromine in cocoa beans in 1841, and the molecule was later synthesized into xanthine by Hermann Emil Fischer. Note that Theobromine can be found in more plants than just the cocoa tree, it's just that it is primarily found in that tree. Theobromine itself is either white or colorless and actually tastes bitter (explains its abundance in dark chocolate particularly). The molecule's chemical formula is C7H8N4O2 and can be seen drawn out below in its Skeletal form.