QuickTTest and QuickTtestX are programmes for calculating means, SDs and SEMs and testing the significance of differences using Student’s t-test. Their main advantage over other statistical programmes is that data can be input not only as individual values (from the keyboard or by import from a text file) but also as mean ± SD or mean ± SEM for groups.
You will need Stuffit Expander or similar utility to expand the files.