I, too, would like some sort of power analysis capability. As LanceGary says, grant applications seem to routinely require such a calculation (but whether reviewers understand it is a different matter!).
statistiXL is a powerful, feature rich data analysis package that runs as an add-in to Microsoft Excel. It has been designed and written by scientists in order to meet the demanding needs of anyone requiring access to a robust, versatile statistical analysis package that is quick to learn and easy to use.