Online resources
Exercises and Matlab codes to accompany Randall LeVeque's finite difference methods book
Matlab codes from Nick Trefethen's spectral methods book
Fortran and Matlab codes at Ernst Hairer's website
Video Introduction to Ordinary Differential Equations Arthur Mattuck's class at MIT in Spring 2004
Ordinary Differential Equations and Dynamical Systems Lecture Notes by Gerald Teschl (University of Vienna)
Elementary Celestial Mechanics using Matlab
by Enrico Onofri (University of Parma) in Computing in Science and Engineering, november issue 2001.
Matlab source code
Homepage of Lloyd N. Trefethen (have a look at e.g. Numerical analysis)
Endre Suli's homepage (scroll down to see the "Lecture notes" section)
Lecture notes by Joseph Flaherty (Rensselaer Polytechnic Institute)
PDE Lecture notes by Bruce Driver (UCSD)