I'm designing a mating board (add-on) for the Rpi and would like to arrange for it to be flush with the top of the highest Rpi component, the USB connector. Given that the height of available sockets varies somewhat, this might take some browsing of data sheets.
I'm also including a USB hub on the mating board, so will need to connect to the Rpi USB connector. I've seen a couple of other boards with what appears to be a custom connector, probably a small PCB with the innards of a Type A plug soldered to it. I'm presently planning something like this myself. I also want to bring the network and audio connectors down to the mating board so that all connections other than HDMI are via a front panel along one edge of the mating board.
I'd guess that these are common problems/requirements for a number of Rpi hackers, and propose that a common solution to them should be found. Likely sales volume is undoubtedly too low to warrant manufactured parts, but a set of drawings including PCB layouts and suitable connector parts might convince a hobby supplier to make a kit available.
Would anyone else second this proposal?