Here is a list of common optimizations. Feel free to add missing ones.
(a) Static optimizations (appropriate to a StaticTranslator)
(b) Dynamic optimizations (appropriate to a DynamicTranslator)
See also the MLRISC project at http://cs1.cs.nyu.edu/leunga/www/MLRISC/Doc/html/, which provides a customizable optimizing back-end written in StandardML? -- ArieVanDeursen.