The weak performance of conventional power system stabilizers to damp inter-area oscillations during severe disturbances can cause the power systems to lose stability especially if the systems are highly oscillatory. To ensure small-signal stability of the systems, increasing interest has been focused on developing supervisory power system stabilizers (SPSS) as a means of remote feedback controllers to tackle the threat of inter-area oscillations to the systems' stability and reliability. The focus of this paper will be on the literature survey of the so far proposed designs and methodologies used for SPSSs to solve the problem of inter-area oscillation damping in order to achieve power system stability.