A collection of Java applets for a number of topics. (All have a good parser, but many are not very visual and none have a description of the algorithm.): Euler data list output -- no visuals; Direction field has nice clean simple graphics; first-order (actually uses Improved Euler) numeric values and a subsequent plotter; Runge-Kutta produces values. Similar applets for second order and systems. Notably there are a number of modeling models (2,3,4 body), planets, double pendulum and spherical pendulum. These models have graphical output, but no description of the underlying equations.