Intel announced Compute Stick at CES. It's a PC running Windows 8.1 on an HDMI dongle. So it can turn any HDMI TV or monitor into a fully functioning computer running Windows 8.1. There's also a Ubuntu Linux version.
Specs:
It is a 4 inch HDMI dongle, with Windows 8.1 pre-installed. It features a quad-core Atom processor, 2GB of RAM, wireless connectivity (802.11b/g/n and Bluetooth) and 32GB on-board storage (with SD card slot), and a USB port to connect mouse, keyboard and other devices.
Pricing:
Windows version of the stick will be available for $149.
Ubuntu version of the stick will be available for $89, but offers only 1 GB RAM and 8 GB of storage.