I've been meaning to post these for some time and finally have a second to! These are some sites I've run across on the net that I thought had some merit in terms of the information they had on the Khmer Empire and Cambodia in general. *g*

http://www.cambodia-travel.com/khmer-civilization.htm

http://www.visit-mekong.com/cambodia/background/history.htm
(from this site there are links to sites covering Laos, Burma, Vietnam and Thailand too)

http://www.angkorwat.org/