The family of spinel compounds of which CdCr2Se4is the prototype has been found to be simultaneously ferromagnetic and semiconducting. Numerous experiments reveal, moreover, that the electronic states in these materials are strongly coupled to the degree of magnetic order. The interaction between the electronic transport and the magnetic state offers the exciting possibility of constructing electronic devices having magnetic control. This paper presents a review of literature on the magnetic, crystallographic, electrical transport, and optical properties of the chromium chalcogenide spinels as they relate to device applications. The prospects of realizing novel devices utilizing these properties are examined.