Maple
Applications. A set of differential equations applications for
Maple. Could be some excellent resources here.
IDEA: Internet
Differential Equations Activities, "an interdisciplinary effort to
provide students and teachers around the world with computer based
activities for differential equations in a wide variety of
disciplines." It looks like they have some great material for
interesting projects, buildup of toxins, chemical reactions, rangeland
ecosystems, salmon migration, small mammal dispersion, etc.
Definitely worth checking out!
The Connected
Curriculum Project at Duke has some interesting modules on
applications of differential equations.