The talk will summarize various porous thin-films developed at the UCLA Micro and Nano Manufacturing Laboratory over the past several years. (1) Micromachining of aerogel-like thin film has been developed, including photolithographic steps and surface micromachining procedures for silica and alumina. Mechanical properties have been measured by direct bending tests with such fabricated free-standing aerogel microbeams. (2) Polysilicon thin film on silicon dioxide, which represents a typical surface micromachining process, has been converted permeable by post-deposition electrochemical etching, allowing on-chip vacuum encapsulation of micro and nano structures finally practical. (3) Silicon wafer with high-aspect-ratio pores serves as a mold in developing three-dimensional nanobatteries. Although most projects start from development of pore formation processing steps, the main goals for all are to explore specific new applications that take advantage of the unique property of the materials or the processing procedures.