MuPAD
http://www.mupad.de/
30 days shareware
SciFace grants you a non-exclusive single-user license to use the Software free of charge if you are a student, faculty member or staff member of an educational institution (junior college or college), a staff member of a non-profit research institution, or an employee of an organization which meets SciFace's criteria for a charitable non-profit organization. Government agencies are not considered educational or charitable non-profit organizations for purposes of this Agreement.
SNNS
http://www.cs.sunysb.edu/~algorith/implement/snns/implement.shtml
The "Stuttgart Neural Network Simulator" from the University of Stuttgart,
Germany supports many types of networks and training algorithms, as well as
sophisticated graphical visualization tools under X11. It has been ported to
many flavors of UNIX.