This research explores different ways to use features of one's own body for interacting with computers. In the future, such "body-based" interfaces may be put into good use for wearable computing or virtual reality systems as part of a 3D multi-modal interface, freeing the user from holding interaction devices. We have identified four types of body-based interfaces: the Body-inspired-metaphor uses various parts of the body metaphorically for interaction; the Body-as-interaction-surface simply uses parts of the body as points of interaction; Mixed-mode mixes the former two; Object-mapping spatially maps the interaction object to the human body. These four body-based interfaces were applied to three different applications (and associated tasks) and were tested for their performance and utility. It was generally found that, while the body-inspired-metaphor produced the lowest error rate, it required a longer task completion time and caused more fatigue due to the longer hand moving distance. On the other hand, the body-as-interaction-surface was the fastest, but produced many more errors.