G*Power is a tool to compute statistical power analyses for many different t tests, F tests, χ2 tests,z tests and some exact tests. G*Power can also be used to compute effect sizes and to display graphically the results of power analyses.
MacAnova has many capabilities but its strengths are analysis of variance and related models, matrix algebra, time series analysis (time and frequency domain), and (to a lesser extent) uni- and multi-variate exploratory statistics. Core MacAnova has a functional/command oriented interface, but an increasing number of capabilities are available through a menu/dialog/mouse type interface. The language and syntax are S-like.
PSPP is a free program for statistical analysis of sampled data. It is similar to SPSS with a few exceptions. PSPP is particularly aimed at statisticians, social scientists and students requiring fast convenient analysis of sampled data.
PSPP can perform several data transformation (including recoding, weighting and handling of missing values), compute descriptive statistics (frequencies, descriptive statistics), compute crosstabs and explore tables, T-tests (one sample T-test, independent samples T-test, paired samples T-test) and one-way ANOVA, bivariate correlationlinear regression, factor analysis (Principal Component Analysis and Principal Axis Factoring), Chronbach Alpha (reliability measure), ROC curve and some non-parametric tests (Chi-square and Binominal).
R is probably the most sophisticated statistics software available. The learning curve is fairly steep, but the availability of hundreds of add-on packages mean that almost anything can be accomplished.
Regress+ includes regression, stochastic modeling, bootstrapping and robust goodness of fit measures.
SOFA is a user-friendly statistics, analysis, & reporting program, with an emphasis on ease of use, learn as you go, and beautiful output. SOFA supports the display results in an attractive format ready to share.