Go to the library and read a little of Foundations of Osteopathic Medicine. It is an extraordinarily boring book, but it will give you countless examples of things that OMM can be used for (in their opinion.) Also, if you really want to impress them, learn about viscerosomatic/somatovisceral reflexes. This is the idea that a visceral problem can manifest itself as a somatic dysfunction (muscle spasm, etc.) and vice versa. In its most common form, a somatic dysfunction exists when something is restricted in motion within its normal range of motion. As example would be the clavicle. When you lie on your back and reach for the sky, the lateral (acromioclavicular)end of the clavicle moves anteriorly and the medial (sternoclavicular) end moves posteriorly. This is the normal motion pattern of the clavicle for this movement. A somatic dysfunction exists when the medial clavicle becomes "stuck" in the anterior position even though you are reaching to the sky. OMT can treat this, generally by using HVLA (high velocity low amplitude) techniques (aka thrust techniques) which move the medial clavicle through the restriction and restore normal range of motion. Examples like this exist throughout the whole body. The cliche example of OMM is using it to treat back pain, but everyone knows about this so I think it would be unoriginal to bring it up in an interview. Feel free to ask if you have any other questions. I'm sure other people will give you other examples. I hope I didn't go overboard