CRC Handbook of Chemistry and Physics
www.hbcpnetbase.com/
Data may be accessed after purchasing a personal or institutional subscription.

Tutorials

Hartree Fock Method
www.chm.davidson.edu/ronutt/che401/HartreeFock/HartreeFock.htm
Example of Hartree Fock method (or self consistent field).

Hückel Theory
www.chem.qmul.ac.uk/software/download/mo/6.pdf
A short tutorial on Hückel theory.

Software
SHMO - Simple Hückel MO Theory Calculator
www.chem.ucalgary.ca/SHMO/
Freeware that performs Hückel molecular orbital calculations with a simple graphical user interface.

WebMO
www.webmo.net
Freeware that provides a graphical user interface for popular electronic structure software (such as GAUSSIAN, GAMESS, and MOPAC). The computational engine must run on a UNIX or Linux server, but the WebMO interface allows for users to generate input and obtain output from any networked computer.