The discovery of new allosteric sites generates opportunities for the identification of novel pharmaceuticals and increases our understanding of basic biological processes. Increasingly, allosteric sites are being discovered in various families of proteins by several methods, paving the way for the development of entirely new classes of drugs with a wide range of chemotypes. New allosteric sites in enzymes have been discovered both incidentally and by directed means, and the mechanisms by which allosteric activation and inhibition occur at these sites have been investigated. By exploring recent structurally well-characterized examples, trends begin to emerge for both the modes of binding and mechanisms of inhibition.