Meta.Numerics has a lot of statistical functionality. It supports t-tests (one sample, two sample, paired), as well as Mann-Whitney and sign tests (non-parameteric alternatives to t-tests), and ANOVA (a t-test extended to more than two samples) and Kruskal-Wallis (a non-parameteric alternative to the ANOVA). And yes, it reports back a P-value with all tests.
