This chapter focuses on a series of further sustainable and/or unconventional wet-chemical methods to prepare single metal, alloys, oxides, chalcogenides and other inorganic compounds in the form of nanoparticles (NPs) at low temperature (<200 °C). In particular, the aim of the chapter is to provide the reader with an overview of further methods not specifically addressed by other chapters of the book, such as hydrothermal, polyol-assisted, continuous-flow and sonochemical methods, as well as radiochemistry and laser ablation in liquid media. A theoretical background of each method, a description of the synthetic procedure and a discussion of the synthetic parameters involved, and their influence on the final features of the products, are given, with the pros and cons of the presented synthetic approaches also outlined. In addition, a description of the state-of-the-art of the compounds obtainable through each approach is presented.