This review highlights recent developments in the synthesis and unconventional applications of nanosized microporous crystals including namely framework (zeolites) and layered (clays) type materials. Owing to their micropore nature nanosized zeolites and clays exhibit novel properties, different from those of bulk materials. The factors controlling the formation of nanosized microporous crystals are first revised. The most promising approaches from the viewpoint of large-scale production of nanosized zeolites and clays are discussed in depth. The preparation and advanced applications of nanosized zeolites and clays in free (suspension and powder forms) and fixed (films) forms are summarized. Further the review is accentuated on the new, non-conventional for porous materials, applications. A comprehensive analysis of the emerging applications of microporous nanosized crystals in the fields of semiconductor industry, optical materials, chemical sensors, medicine, cosmetics, and food industry is presented. Finally, the future needs and perspectives for nanosized microporous materials (zeolites and clays) are addressed.