Two years ago, HDMI dongles were not even a blip on the market but since then, they have quietly established themselves as one of the more popular computing form factors on the market. And their coming of age has coincided with the rapid acceleration in the development of affordable, powerful ARM-based system-on-chip.
For instance, the Reko MK809 III is one of the first HDMI dongles to come up with a quad-core SoC (a Rockchip RK3188 Cortex-A9 model clocked at 1.5GHz paired with a Mali-400 GPU) and 2GB of RAM. In theory (and in theory only), you should be able to run Windows RT on it.
Other features include 8GB onboard storage, a microSD card slot, Android 4.1.1 Jelly Bean, Wi-Fi, Bluetooth, support for 3D and 2.4GHz connectivity. It comes with two microUSB ports and a standard USB one.
Expect many others like the MK809 III to come to the market in the next few months with a mix of Cortex-A7, Cortex-A5 and Cortex-A9 devices. DealExtreme is already stocking it for $77.70 or about £49, which is about twice the price of an entry level HDMI dongle and in the grand scheme of things, not a lot of money.