Discreta Discreta: A program to construct t-designs with prescribed automorphism group. C++ source code free to download, with GAP interface. (Software) http://btm2xl.mat.uni-bayreuth.de/discreta/
GOSSET GOSSET: A general-purpose program for experimental designs, by N. J. A. Sloane and R.H. Hardin. Free download of beta-test C source files. (Software) http://www.research.att.com/~njas/gosset/
DESIGN Package for GAP DESIGN Package for GAP: A package for classifying, partitioning and studying block designs in GAP 4.3 by Leonard H. Soicher. Free download in .tar.gz format, documentation in PDF. (Software) http://designtheory.org/software/gap_design/