Macroporous silicon (MPS) is a versatile material that since its origin in the early 1990s has seen intense research and has found applications in many fields. MPS is a key technology in photonic crystals research, and optic and photonic applications are its main applications. However, this chapter is devoted to several of the non-photonic uses of MPS. In particular, new electronic and MEMS devices and applications will be described. Furthermore, in this chapter, the technology of MPS fabrication will be presented.