Depending on how much time you want to spend in Cambodia, there are a few things that are a must. Probably one of their nice beaches, Phnom Penh, the capital, and Siem Reap, where you can see the truly amazing temples of Angkor Wat. This is Angkor Wat, if you are interested ;-). A post about it soon. If you have a month or so you can spend time visiting all of the south and some remote parts in the north, which is not very much explored and, apparently, has many nice places to go.