I have not traveled to Cambodia yet but I plan to in the near future. Blogger betterdays ( Preetamrai) just posted a blog entry about the e-visa process in Cambodia that should make it easier to get a visa to Cambodia. It costs $25 US total for a 30 day tourist visa and takes about three days to process. After it is processed, you can print it out and bring it along with you when you travel to Cambodia.
For travelers entering from Vietnam, make sure you to enter Cambodia through the Bavet (tour buses from Saigon all go through Bavet on their way to Phnom Penh). The visa are not valid at other Vietnam/Cambodia ground port of entries. The visa are valid for flights into Phnom Penh and Siem Reap international airports as well.
Go to the Official e-Visa by Kingdom of Cambodia for more information.
(Image Source: betterdays (Preetamrai))
Yes, it would be nice if Vietnam could offer a similar program 🙂