PAST, free software for scientific data analysis
I was just sent a link to PAST free software for scientific data analysis, with functions for data manipulation, plotting, univariate and multivariate statistics, ecological analysis, time series and spatial analysis, morphometrics and stratigraphy.
Current version (February 2016): 3.11 runs under Mac OSX 10.8 and later.
Hammer, Ø., Harper, D.A.T., Ryan, P.D. 2001. PAST: Paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4(1): 9pp. http://palaeo-electronica.org/20011/past/issue101.htm
I've added it to the page of data analysis packages for Mac OSX.