There are all sorts of interesting statistical applications on the web, many of which are useful educational tools.  Below are links to some that we've found.  If you find others and think they're worth adding to this list, please e-mail the site's URL to Jerry Reiter at jerry@stat.duke.edu.   Have fun!

Regression and correlation

• Guess the correlations of random scatterplots of points.
• Draw your best guess at a regression line and see how well you do compared to the least squares line.
• See how individual points can affect regression lines.

Probability

• Investigate the effects of changing the standard deviation on the shape of the normal distribution.
• Simulations of interesting problems in probability, including the birthday problem, the coupon problem, and Banach's matchbox problem.
• Simulation of the Monte Hall problem: should you switch doors or not?

• Normal  approximation to the binomial.
• Ball drop that simulates a normal distribution.
• A demonstration of the central limit theorem with skewed distributions.

• Confidence interval coverage.