The cover picture (design by Dr. A.N. Shipway) shows a selection of colloidal "nanoparticles", composed of metallic or semiconductive materials, which may be assembled onto gold or glassy (ITO) surfaces. These organized, hybrid materials exhibit electrical, optical, and catalytic properties that differ from the bulk materials and find application in an increasing number of situations. In all cases, the nature and dimensions of the nanoparticles, the linkers used to immobilize them, the surface to which they are bound, and the organizational style are critically important. Further details are given in the review by Willner et al. on pages 18 - 52.