Normal Distribution Interactive Tables
Interactive normal cdf (cumulative density function) calculator
Another Normal GUI (Graphical user interface) calculator from Stisci, which also includes other distributions
Yet another visual normal calculator
Central Limit Theorem
Discussion with animated visuals in the hyperstat home page
The best simulation demonstration of the central limit theorem I found is developed at Rice and allows you to change the underlying distribution.
General Information about the Normal Distribution also check out the Quincunx demonstration
Discussed in the Hyperstat online Textbook which also has information on the normal approximation to the binomial distribution