The essence of combinatorial chemistry or techniques involving "molecular diversity" is to generate enormous populations of molecules and to exploit appropriate screening techniques to isolate active components contained in these libraries. This idea has been the focus of research both in academia and in the pharmaceutical or biotechnology industry. Its developments go hand in hand with an exploding number of potential drug targets emerging from genomics and proteomics research. When the editors of Current Topics in Microbiology and Immunology encouraged us to assemble the present volume on...