A handheld rig is pretty much what it sounds like; any rig that is held or attached to the camera operator’s body. Probably the most famous is the Steadicam™. Many manufacturers over the years have done their version of this great rig, both in a vest-style full Steadicam rig and a version for smaller cameras that is literally hand-held. The Shock Corridor Stabilizer falls into this category. It certainly has been the favorite of filmmakers buying this particular book over the years!
You will also find a rig that holds your camera inches off the ground for cool traveling shots called The Sweet Smell of Success Pooper-Scooper Cam. The City Streets Circle Rig was designed by filmmaker Mike Figgis for his film Timecode