Chassis builders, Silverstone, have just announced the release today of their new Raven RVZ01 PC case. And it bears more than a passing resemblance to Valve's Steam Machine prototype. The Raven RVZ01 is the follow up to the RV01 Silverstone released some six years ago, and shows how times and aesthetics have changed. Gone are the overly-angular edges of the original, instead gone for a simpler, smoother chassis design.
Personally I've been waiting for third-party manufacturers to start creating small form factor, mini-ITX chassis capable of housing a horizontally-mounted graphics card - a la the Steam Machine prototype. That's the only way to get the height of a machine with a discrete GPU down and make it look less like a hefty traditional PC.
The Silverstone PCIe riser plugs into the mini-ITX motherboard and allows you to drop in any dual-slot graphics card up to some 13-inches in length. That's enough space even for a chunky AMD card, though cooling of a GPU that toasty might be tricky in such a small form factor. Still, it's that relatively slim-line look that sets this performance case aside from much of the mini-ITX herd.
Cases like Corsair's Obsidian 250D and EVGA Hadron Air are lovely chassis, and great to build a small form factor machine into, but will still look thoroughly out of place under your TV in the living room. If they even fit under there in the first place.
Obviously there are limitations to the component choice, motherboard aside. The primary concern has to be the power supply - you need an SFX scale PSU, but luckily Silverstone make those in capacities up to 450W. You'll also need a slimline CPU cooler too, with a height of less than 83mm. Again, Silverstone can help with that, but others, like Gelid and Zalman also make compatible, effective chip chillers.
The Raven RVZ01 isn't going to be cheap, but at some £50 / $70 it's really not bad value and will allow you to build a very slim PC for the living room.