I've been hearing awesome things about Amazons new TV box lately. Not available here in the UK via Amazon yet, but -
http://www.ebay.co.uk/itm/BRAND-NEW-...-/141248974547

Sideloading Apps, most already included (Plex Home Theater as Standard!) and also the possibility of adding Google Play Store to it already.
I'm seriously looking into owning one myself once I've read a few more reviews, especially at that price.

Perhaps to replace my Acer Revos (which would have been the number one choice a couple of years ago).