The Schulenberg Factorization Suite:  Freeware (available for download).  This package includes the following:

                RMTEST -- Rabin-Miller Primality Test program 

            FACTOR2 -- Pollard Rho factorization program (Brent algorithm) 

            FACTOR3 -- Multi-polynomial Quadratic Sieve (MPQS).  Handles "hard" numbers of up to 100 digits

Our implementation of an Elliptic Curve Method (ECM) is nearing completion.  This method will  be an ideal complement for our current MPQS algorithm.  We will also soon issue a modified version of our MPQS algorithm which will utilize the double-large-prime method, and which will handle hard numbers of up to 130 digits in size.

In the more distant future we hope to begin development of a  Number Field Sieve (NFS) implementation.  We would be interested in hearing from anyone who has a desire to collaborate in this effort.