Scratch-Pad Memories (SPMs) are considered to be effective in helping reduce memory energy consumption. However, the variety of SPM management techniques complicates the choice of the right one to implement. In this paper, we first give a synthesis on existing SPM management techniques for low-power and -energy outlining their comparative advantages, drawbacks and trade-offs. Then, we propose a new general classification which encompasses most existing research works. This classification has the advantage of clearly exhibiting lesser explored techniques, hence providing hints for future research.