I just ran into this auction for a used REWO GH2 Specific Video Cage. I'm sure someone out there might find this useful. This is a great product, but typically priced in the $400 dollar range. EOSHD has a nice write up about this cage (found here).
The REWO cage allows you to mount several accessories to the body of a GH2, and will clamp 15mm rails if you plan to use a Follow Focus or other 15mm accessory. I'm curious if it could work well to fit a Sony NEX, OM-D, Sony RX1, or other similar small body HD camera. I doubt it could fit the new and slightly larger GH3. The current price (as of writing) is set to $82 US dollars. Check out the auction following the link (click here).
Used: REWO GH2 Video Cage Bracket - via eBay