If you have the chance to get to Lao (we combined this four years ago and just came back from laos again) go to Thakek in the middle of Lao. It is such great climbing there in amazing rock with lots of tufas. And a very nice climbing camp with yummy food. :-)
There's climbing an hour or so outside of Phnom Penh, Cambodia. Basically a couple huge boulders with a handful of bolted routes. Leave Phnom Penh very early in the morning, so you're at the crag when there's a little bit of shade. One of the best routes there is a steep 5.9; there's also easier and harder stuff.
There's also a developed crag north of Battambang. You can see it from the highway as you head from Batambang or Siem Reap toward Piopet on the border. The cliff is on a hill on the north side of the road.
Lots of other crags, but they are generally very unsafe due to UXB.