Core BioPerl 1.x code
Extensible, Beautiful Charts for Perl
Perl interface to the GNU Scientific Library
Scientific computing with Perl
Gnuplot-based plotting backend for PDL
Statistics modules in Perl Data Language, with a quick-start guide for non-PDL people. They make the PDL shell work like R, but with PDL broadcasting (fast automatic iteration) of procedures including t-test, linear regression, and k-means clustering.
simple statistics from the command line