SHAPE's CP33 Multi-Purpose Mounting Cheese Plate will let you add various accessories and devices to your camera rig. Just attach it to any two 15mm rods on your rig, and you'll have a total of thirty-three 1/4-"20, 3/8"-16, and 10/32" threaded holes to work with.
You can attach accessories to both the front, back and sides, and in some applications at the same time -- for example, you can have a battery plate on the front side and an AJA Ki Pro recorder on the back. The holes on the side are the 10/32" holes. Four are available on each side for audio receiver brackets. Another great accessory you can attach is an articulating arm. You can actually attach a bunch of articulating arms, each pointing in a different direction.
The plate is 1/4"-thick and is precision-machined into one whole, aluminum piece. It comes with sets of screws for attaching the Ki Pro, IDX battery plates and Anton Bauer battery plates.