You might have thought someone would have already done this? Apparently not, just released this week is the worlds first USB 3 Mini-Itx motherboard from Gigabyte, the GA-H55N-USB3.
Based on the H55 chipset for LGA1156 processors, the board supports up to a Core i7 870 processor with up to 8GB of DDR3 RAM. The board also features a single PCI-Express slot making it a possible to create a nifty little gaming rig in an unthinkably small enclosure. If you are just planning on lighter work you can use an i5/3 processor with integrated graphics and have the standard HDMI, DVI and VGA interfaces.
Not content with just USB3 support, Gigabyte have also included 3xUSB Power Boost, which allows you to charge that shiny new iPad, iPhone, or iPod Touch. You can charge your device while turned on, or take advantage of the special On/Off charge support which allows charging all the time, even when the PC is switched off!
For more info head on to the Gigabyte website. All images credit Gigabyte.