I bought a micro-USB to HDMI MHL cable on a lark down at Central Computers on Howard St. in San Francisco just to see if I could get video-out on my CM-modded HTC One. I hooked it up today to our Samsung TV just to see and it came up immediately! Pretty cool that it just pushed the video-out without a problem or additional configuration. My guess is any micro-USB to HDMI cable should work. Here are some pics of the $15.95 one I bought from Central that for sure works.
Here is the cable in the bag. It is a pretty generic model. I bought it because it was the only one that really didn’t make a reference to Samsung phones. My guess is though, it probably doesn’t matter as long as the cable is to the MHL standard.
I was so shocked it all just worked, I have yet to test things like Netflix, and other Android audio/video apps.