Below are a few applets I've written in R. I hope you find they work in every browser/operating system / computer combination.

CorrelationAn applet that enables users to guess the correlation of randomized data and to explore the effect of sample size and outliers on correlation.

Sampling DistributionsAn applet illustrating sampling distributions.

PowerAn applet illustrating the relationship between power, alpha, beta, and sample size.