For PPL, either the Jeremy Pratt or Trevor Thom books should be sufficient. For extra information, Human Factors for Pilots by Roger Green is good; it's standard is between PPL & CPL. For CPL and above, a ground school will provide manuals.
There are interactive CD-ROMs on the market but I don't know of any websites (other than those belonging to various schools for which you need to register and pay) which deal with human factors.
Much of it is school biology so you could try BBC learning and other educational websites.
Cheers
Whirls