(an always-in-revision list of resources. Starting with the basics:)
Anglophone Students
Texts
Modern Spoken Cambodian Franklin E. Huffman
Colloquial Cambodian David Smyth
Beginning Khmer Frank Smith
Heritage Khmer Frank Smith
Courses
Southeast Asian Summer Studies Institute
Advanced Study of Khmer
Francophone Students
Web Resources
StudyKhmer.com
http://khmaesuolhien.wordpress.com
Modern Spoken Cambodian (Online)