Image: Cargo Collective

In keeping with the three-legged furniture theme, is Trialog, a wooden chair designed by Philipp von Hase to be sat on backwards as the chair's backrest also serves as an armrest.  The designer is of the opinion that sitting in this manner gives a more upright and proactive posture and can improve body language.  In addition to the reverse sitting, a person can also choose to sit sideways or conventionally.

Images: Cargo Collective