In this presentation, I will describe the synthesis of six types of colloidal Au and Ag nanocrystals and briefly discuss their plasmonic properties and applications. They are Au nanospheres, Au nanorods, Au nanobipyramids (NBPs), Au NBP-directed Ag nanorods, Au NBP-templated Ag nanostructures and Au nanoplates. All of them have very narrow size distributions. Their sizes and therefore their localized plasmon resonance energies can be readily varied over broad ranges by carefully controlling the synthetic conditions.