A cancer patient treated with a molecule found in algae-eating sea hares native to the Indian Ocean. Jet fuel produced by algae in open urban ponds. A tonne-scale synthesis of pharmaceuticals using enzymes from a green biofilm growing in your backyard. The first example is a reality, but the others are not necessarily confined to a utopian future. All these scenarios can be linked to blue-green algae (cyanobacteria). These talented microbial biochemists generate a vast set of unique secondary (specialized) metabolites. Initially infamous for being potent toxins that have resulted in human deaths, some cyanobacterial secondary metabolites have proven useful and are currently used in the clinic. The enzymes that biosynthesize some of these compounds are likewise remarkable and could find future industrial use. Here, I discuss some aspects of past and current secondary metabolite discovery in cyanobacteria, the potential impact of these small molecules for human activities and how the study of their biosynthesis has unearthed exciting new enzymatic reactions.