Maxima, a Computer Algebra System Maxima, a Computer Algebra SystemThese are packages we either can't include in the main Maxima package for legal reasons or haven't gotten to yet.
If you know of old Macsyma code still out there, please tell us about it so we can list it here, or perhaps if the license is compatible even add it to the distribution.
An implementation of Gosper's and Zeilberger's algorithm for proving and finding indefinite and definite hypergeometric summation identities. Developed by Fabrizio Caruso.
UPDATE: the Zeilberger package is included in Maxima 5.9.2 and later.
A series of interesting Macsyma packages. Commercial use is not permitted without consent of the authors.