Here is a program with a very limited audience (researchers, statistics students). It replaces some of the more common statistical tables. It will compute the p value (probability of a more extreme result) for the Z, t, F, and chi square distributions. Or, for a given alpha level, it will calculate the corresponding critical value of the statistic. For the Z and t distributions, you have your choice of one tailed or two tailed tests. For the t and F distributions it will also report the corresponding value of Eta. Eta is a measure of effect size - the nonlinear correlation between the independent and dependent variables. Eta squared can be interpreted as the proportion of explained variance. For me, it is quite nice to have these functions available on my touch phone (Samsung Omnia). Authors frequently neglect to report effect size but I can just whip out my phone, plug in the t or F value, and see for myself. Useful for improving accracy in interpreting research results. I now return you to the real world . . .