Digiscoping is snapping images with a digital camera pointed through the eyepiece of a spotting scope or telescope. I've been dabbled in it for several years and just got the attachments for my Canon G6.
I calculate I get magnification of about 42x, or the equivalent of a 2100mm telephoto lens. It works pretty well for shooting chipmunks from about 20 yards. The telescope mirrors the image right to left so I had to flip this in Photoshop to get the orientation correct:
Focusing is partially manual, and it's probably impossible to follow a moving subject. I still want to get a real telephoto lens for my DSLR, but I'll wait a while until I have the opportunity to use it effectively. (As a Canon shooter, by "real" I mean a Big White Lens such as the 500mm f4.) Until then, digiscoping should work well enough for shooting nests and other stationary or predictable subjects.