china sells tons of cheap arm based android devices that connect to your HDMI display on your TV. i got mine for 60 bucks back when, i think they are around 40 bucks now, newer ones more expensive of course.
Chrome Cast - Send stuff to your tv from the cloud. Chrome Cast requires an HDMI slot, a power cable and a host PC. It was reported that screen share is meh but you can watch netflix and hulu etc because you send the chrome cast what you want and it pulls the video via wifi through your router.
Raspberry Pi - This is a tiny computer and if you buy a kit it usually comes with an 8GB sd loaded with an Xbox Media Center (XBMC) linux distro. This requires a power source, hdmi input, ethernet cable or compatible wifi module. Options also include bluetooth support to turn your android phone into a remote. Can do searches of your network hard drives, Hulu, surf the web, watch youtube. Does NOT support Netflix at this time. Also this allows you to experiment with programming linux as there are many tutorials and the r-pi is a very versatile microprocessor.
Android USB Stick - A while back a bunch of Android on a stick usb drives came out. Plug this into any usb port on a tv/monitor, connect a keyboard and mouse and away you go. Full fledged android with all of its support and goodness.
Hope this gets you started in your search. Which one you feel is best is up to how much leg work you want to put in and the features each offers out of the box.