The Manfrotto Nano Clamps are great little gadgets, but come a little steep. I currently have my hands on another cheaper set of small mini nano-style clamps, and lately they've been performing a hundred different duties. I've been using mine mainly with the Power Friction Arms, since it has both a 1/4 x 20 mount and a 3/8" mount on the backside to mount microphones, portable audio recorders, and LED lights in random places. It's a completely metal unit with no plastic parts. This version has the 'toolless' driver lever which can be repositioned after clamping. If you've been eyeballing those Nano clamps for while, here lies a cheaper option.

Mini Nano-Style Accessory Clamps