I haven't seen any but I've been hoping for some. Even starting with a 'docking cable' would be nice, something that plugs into the power port on one end and splits into DsiplayPort & USB 3.0 on the other end. Could be a handy 'single plug' solution to hooking up to existing monitors and keyboards without needing the full dock (e.g. if you move around a lot to different locations).
I'm also keen to see what other accessories people come up with to utilise that port.