Software

AUTO
The Continuation and Bifurcation Software for Ordinary Differential Equations. Topics include Bibliography, Documentation, and Download.
http://indy.cs.concordia.ca/auto/

Diffpack Online
An object oriented development framework for the solution of partial differential equations. Free demo CD. Online ordering.
http://www.diffpack.com/

Dr. Hanley's Science Graphs
Enter first and second order non-linear ordinary differential in analytical form. The program will generate a numerical solution to the equations and graph multiple curves on a single graph. Can also be used for algebra and calculus formulas. Includes illustrations and free demo.
http://www.hanleyinnovations.com/sgstandard.html

FlexPDE
A general, script driven solution system for Partial differential equations, including equation interpretation, mesh generation, numerical solution and graphical output.
http://www.pdesolutions.com

ODEcalc
An ordinary differential equation (ODE) calculator. State your equation and boundary or initial value conditions and it solves your problem. Plots solution, y, and derivative, ydot, versus x. Solves nth order ODE as IVP and BVP.
http://www.digitalcalculus.com/demo/odecalc.html

Phaser Scientific Software
A Universal Simulator For Dynamical Systems
http://www.phaser.com

XMDS: eXtensible Multi-Dimensional Simulator
A code generator that integrates equations translating from XML to C++. Unix/Windows. Free to download under GPL.
http://www.xmds.org/