Web page links to many of the more widely used programs offer convenient access:

Pacific Northwest Labs, suite of programs: NWChemDESCRIPTION
The MacroModel program by Schrodinger DESCRIPTION
The Gaussian suite of programs DESCRIPTION
The GAMESS program DESCRIPTION
The HyperChem programs of Hypercube, Inc. DESCRIPTION
The CAChe software packages from Fujitsu DESCRIPTION
The Spartan sofware package of Wavefunction, Inc. DESCRIPTION
The MOPAC program of CambridgeSoft DESCRIPTION
The Amber program of Prof. Peter Kollman, University of California, San Francisco DESCRIPTION
The CHARMm programDESCRIPTION
The programs of Accelrys, Inc.DESCRIPTION
The COLUMBUS programDESCRIPTION
The CADPAC program of Dr. Roger Amos DESCRIPTION
The ACES II program of Prof. Rod Bartlett. DESCRIPTION
The MOLCAS program of Prof. Bjorn Roos. DESCRIPTION
The MOLPRO quantum chemistry package of Profs. Werner and Knowles DESCRIPTION
The Vienna Ab Initio Simulations Package (VASP) DESCRIPTION
IQmol is a free open-source molecular editor and visualization package.DESCRIPTION
IBM's Qiskit is an open source SDK for working with quantum computers at the level of pulses, circuits and algorithms.DESCRIPTION
IBM's Quantum Experience offers cloud access to the most advanced quantum computers available. Learn, develop, and run programs on our systems with IBM Quantum Experience DESCRIPTION
The Quantum Espresso project DESCRIPTION
The PyQuant python library DESCRIPTION
The QuTip Quantum Toolbox is an open-source python software package for simulating the dynamics of open quantum systemsDESCRIPTION
QMCTorch is a pytorch (fast) implementation of real space quantum monte carlo simulations of molecular systems. Those interested in applications of neural networks in chemistry might enjoy this DESCRIPTION
The open source quantum chemistry library Psi4DESCRIPTION
The ORCA suite DESCRIPTION
The Molecular Workbench is a cool tool for visualizations, interactive simulations for teaching, and learning science Probably Move to Educational Resources Page
Phet provides interactive simulations for science (quantum mechanics, etc...) and math Probably Move to Educational Resources Page
For fans of statistical mechanics, diagnlarguements.com provides multiple Ising Model visualization suites Probably Move to Educational Resources Page
The University of St Andrews hosts a wonderful quantum mechanics visualization toolkit - QuVisProbably Move to Educational Resources Page
Professor Daniel Schroeder hosts a variety of educational physics software suites Probably Move to Educational Resources Page
Falstad's math and physics applets are a good resource for quantum mechanical visualizations for education purposesProbably Move to Educational Resources Page
Physlet Quantum Physics is a remarkably vast and extensive quantum mechanics visualization projectProbably Move to Educational Resources Page
This project is an absolutely stunningly beautiful fluids interactive simulation Probably Move to Educational Resources Page
Quatomic has developed a modern software suite for Quantum Optimal ControlProbably Move to Educational Resources Page
WebMO is a web-based interface to computational chemistry packages.Probably Move to Educational Resources Page