There are a myriad of devices that x-ray and C-SAM®
can be applied to. To see some specific case studies click here.
Specifically for C-SAM® the short answer is basically any device that is not constructed to have air gaps or is not round. A typical device would be a plastic encapsulated microcircuits (PEM's) where MSL testing could cause internal damage, or prior to doing a DPA, or to screen a particular lot for defects. Other devices that are commonly scanned acoustically are ceramic capacitors, heatsink attachments, hybrids, or devices on PCB's.
As far as X-ray, PEM's are also fairly common. In addition to PEM's, devices that do contain gaps or are round in nature such as ceramic IC's and CAN or AXIAL devices are good x-ray candidates. X-Ray is also ideal for finding broken or bent bondwires as well as potential counterfeit devices.
For more basic information on PEM's click here