You could also take an existing TV mount that you may have already and put some half-couplers through the wall bracket section. (Not off the shelf per se but combining two off the shelf products)
I have also seen two peices of unistrut bolted to the TV and two half couplers attached to the strut.
Ah, those are nice products. I like those Light Source brackets, but our balcony edge has a bit of a "belly" to it, so I'd need to make sure they weren't too long for that. @Amiers, I take it that clamp is adjustable to a certain degree?
I'll admit, I have entertained the idea of drilling 1/2" holes in the plate it's currently on and mounting it to a pair of Mega-Clamps, but figured that might not be kosher.
I have 2 mounted on or balc rail. 1 is mounted to the drop down pipe of the projectors with u bolts to a small arm wall mount. Works well. The other one I used a Cheesebrough Pipe Adapter and picked the length of pipe I needed and then to a pole mount tv mount. Works great. Used lightweight LED tv's so there is anot a lot of weight hanging.
Thank you all for the wonderful suggestions. I got the TV mounted last month, and I thought I'd give you an update. Turns out, that "LCD TV" was actually a huge, heavy plasma. But, it still worked as expected. I basically took the original mounting plate (which was ~1/8" steel), and drilled two 1/2" holes to accept Mega-Clamps. Here are some before & after pics. There are three safety cables involved: two for the mounting plate and one for the TV itself.