So I am looking to digitize my massive old collection of photos (long overdue) and I was wondering... has anyone ever tried or knows of a good photo scanning service? Where you send them a box and they return it with a CD or something.

What do you call "massive" ? How many images approximately? 

I had a Canon printer, and scanner in the USA. Got it on sale at Office Max for $60 USD, a similar unit in Big C in Buriram was selling for 5800 baht (ouch). We scanned a large box of photos before we moved and it took a while but worked really well. The canon software would also save each picture as a separate file as long as there was space between the pictures on the glass (2-4 pictures at a time).

OP, Printer/scanners are cheap here,  grab one and do it yourself, store on a hard drive, backup in the cloud, print the ones you like etc. It may be hard to find someone that does it because people do it themselves and there wouldn't be much demand. You dont even need a computer as some models will scan straight to a usb device.