My wife and I have made an admittedly minimal effort to teach our son Khmer, the language of Cambodia. When he was born, we made the conscious decision to continue speaking English, because my wife needed to continue polishing her language skills as she attended college.
That said, we still try to expose the little one to Khmer. And thanks to Phal Ngim, there's a host of iPhone and iPod apps that make it fun and interesting for our son. Obviously, you may scoff at buying a $200 gadget just to expose your child to Khmer vowels, but iDevices have become ubiquitous and there are always deals.
His favorite of the Khmer-education apps is — unsurprisingly — iKhmerZoo. It features an assortment of animal flash cards, complete with the name written in Khmer and the pronunciation of the word. He also likes iKhmerFruits. I actually found iKhmer123 to be a good refresher, as I always had trouble reading Khmer numbers.
The apps are a little rough around the edges, especially if you're used to the headline apps in iTunes. Phal Ngim would benefit from some time in a professional recording studio, but the apps are functional and educational.
There are many more Khmer-focused apps by Phal Ngim on iTunes, including one apparently targeting adult foreigners looking to communicate in Cambodia: iSpeakKhmer. I haven't tried that one, but if it works as well as his other apps, it's worth the $2 to help you properly say "sous a day."