I've been thinking about my favorite molecules lately, and below is a partial list:
Water
Glowing Luciferin
Allergic to Antibodies
Muscle
Smelliest Aromatic hydrocarbons
Deep Sea TAQ
Melting with GroEL GroES Chaperonin complexes
Silicates and Ceramics
Black and White Rhodopsin
Bloody Hemoglobin
Plastic Polymers
Pictures of Silver nitrate
Heavy Metal
Jason Sumner