The venoms of predatory cone snails represent a rich combinatorial-like library of evolutionarily selected, neuropharmacologically active peptides. A major fraction of the venom components are conotoxins--small, disulfide-rich peptides that potently and specifically target components of the neuromuscular system, particularly ligand- and voltage-gated ion channels. This review focuses on Conus peptides, which act at nicotinic acetylcholine receptors. These nicotinic antagonist peptides from Conus are broadly divided into two groups: those that act at the neuromuscular junction and those that act at subtypes of neuronal nicotinic acetylcholine receptors. The latter include peptides specific for the alpha 7, alpha 3 beta 2, and alpha 3 beta 4 nicotinic receptor subtypes. The degree of specificity exhibited by these peptides is remarkable, particularly given their relatively small size. As a group the nicotinic acetylcholine receptor-targeted Conus peptides represent an increasingly well-defined set of tools for probing the structure, function, and physiological role of nicotinic acetylcholine receptors.