The following web sites have information about quantum computing, and have code for simulating the action of a quantum computer. I found these sites to be great resources during my study of quantum computing.
http://tph.tuwien.ac.at/ oemer/qc/qcl/qcl.html
http://tph.tuwien.ac.at/ oemer/prakt/prakt.html
http://www.openqubit.org/