- OMF
- Check out the OMF International (UK) website - it's excellent.
The OMF Cambodia website isn't far behind.
- Our supporting churches:
Holy Trinity, Old Hill
/ Riverside Overseas Mission (aROMa)
St John's Church,
Harborne, Birmingham 
Wapping Community Church
- Other favourites:
All Nations Christian College, where we trained (highly recommended)
Cambridge Papers, for great thinking on contemporary issues
Global Nomads, on Third Culture Kids
Not to mention the links scattered throughout the site (especially at the bottom of the Resources page)...