Be warned -- not all the cheap cables are created equal. The one (so far) that I got was a dud.
I was thinking how great it was to finally have a portable device that can do pretty decent video output on the go, but then I saw this was HDMI only. I was thinking it would be great for the car for the kids to watch something, great to bring into the hotel (or wherever), or even use it at school or the office for a slideshow via a projector, but even in these modern, techie times, how many car video systems offer a HDMI connection? How many hotels? How many projectors at the office or school? Yeah, that would be none.
HDMI output is nice bragging rights, but it's...well...stupid. Just a regular ol' composite video/audio out would've been the most compatible and therefore useful. No, not the greatest resolution, but c'mon...it's a frickin' phone. The largest capacity SDHC card anyone can reasonably afford at the moment is 16GB. At the most, that's about 25 movies encoded with questionable quality for a big screen. And, oops...our SD card slot is under the battery, which is under a three-layer Seidio Innocase Rugged for me. Yeah, I'm not switching out that 16GB card anytime soon, especially not because the kids are whining about the same old assortment of movies.
My declaration: Not a useful feature.
Therefore, I use the HDMI cable for....nothing.