- MathWorld's probability page - http://mathworld.wolfram.com/Probability.html
- Free PDF probability book, by Grinstead and Snell - http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/book.html
- Distribution simulations - http://people.clarkson.edu/~whooper/applets/applets.html
- Binomial distribution - http://www.capdm.co.uk/demos/software/html/capdm/qm/binomialdist/usage.html
- Poisson distribution - http://www.math.uah.edu/stat/applets/PoissonExperiment.html
- Normal approximation to binomial - http://www.stat.wvu.edu/SRS/Modules/NormalApprox/normalapprox.html
- Central Limit Theorem and sampling distributions - http://onlinestatbook.com/stat_sim/sampling_dist/index.html
- Probability by Surprise, from Stanford - http://www-stat.stanford.edu/~susan/surprise/
- Some statistical applets from Freeman