Spin degrees of freedom of electrons already play active roles in current technologies---read heads of magnetic hard drives and magnetic random access memories (RAMs). These devices are based on magnetic metallic structures. A strong push for employing spin in semiconductors is emerging under the name of spintronics.
I will review the basic concepts of this field and discuss some of my contributions such as magnetic diodes and transistors, as examples of classical spin devices. Spin electronics also deals with spins on the nanoscale where the spin is likely to be used as a qubit for quantum information processing.
I will show an example of a quantum spin ``device''--an entanglement distiller--based on adiabatic passage of correlated electrons in coupled quantum dots. The distiller spatially separates singlet and triplet states from a common unentangled state.