Education

Read/Write Khmer:
How to Type Khmer Unicode (English)
Khmer-English Dictionary Excellent
Online Khmer-English Dictionary Requires Khmer unicode.
Online English-Khmer Dictionary Khmer unicode not required.
How to read and write Khmer (alphabets and numbers)
Hannah learns Khmer

Literature:
Khmer Folktales (Khmer)
Promoul Pheasith Khmer (Khmer) - Samdech Choun Nath
Sim Naek Bor Laan (Khmer novel)
Khmer Folktales from the Buddhist Institute. You need Khmer Unicode installed on your PC to read these articles.
Tum Teav - English translation by George Chigas

Culture:
Komnot ompee panyaha Preah Vihear (Khmer)
Preah Vihear: A Khmer Heritage (English) - Kenneth T. So
Preah Vihear Proposal by RGC

History & Politics:
Pol Pot and Kissinger (English) - Edward S. Herman
History of Cambodia (Khmer) by Adhemard LeClere
The Political Ecology of Transition in Cambodia 1989-1999: War, Peace and Forest Exploitation (English) - Philippe Le Billon, 21 Pages

Reference:
How to Type Khmer Unicode (English)
Online Khmer-English Dictionary (free)
Cambodia Country Profile (English) - Cambodia from CIA World Factbook 2006. 11 Pages.
Preah Vihear Proposal by RGC
First Contact in the Mekong 2008 Final Report Animals (English)
Modern Myths of the Mekong (English) - Matti Kummu, Marko Keskinen, Olli Varis (eds.) - A critical review of water and development concepts, principles and policies
Breast Cancer Awareness Cambodian English Pamphlet (Khmer/English)
Micronutrient Deficiencies and Interventions in Cambodia (English) - Johnston R., Conkle J., 2008
Buddhism, And the No-Soul Doctrine (English) - Leoni Hodgson. 13 Pages.