LanQ Quantum Programming Language - LanQ is an implementation of an imperative quantum programming language supporting execution of multiple processes in parallel. - http://lanq.sourceforge.net/
QuCalc - Library of Mathematica functions whose purpose is to simulate quantum circuits and solve problems of quantum computation. - http://crypto.cs.mcgill.ca/QuCalc/
Bibliography on Quantum Programming Languages - Bibliography by Simon Gay gathering references to papers about theoretical aspects and implementations of quantum programming languages. - http://www.dcs.gla.ac.uk/~simon/quantum/
Artiste Company - Commercial site offering software for Quantum Computer simulation and simulation of other quantum mechanical behavior. - http://www.ar-tiste.com
Quantum Computer Emulator (QCE) - A Windows based simulator of quantum computer hardware. Provides an environment to execute quantum algorithms under realistic experimental conditions. - http://rugth30.phys.rug.nl/compphys0/qce.htm
libquantum - A C library for the simulation of a quantum computer. It provides all important operations and the simulation of decoherence effects. - http://www.enyo.de/libquantum/
QCL - Quantum Computation Language - Documentation and the source code for the QCL, high level, architecture independent programming language for quantum computers. - http://tph.tuwien.ac.at/~oemer/qcl.html