Basically, I build static sites for some small businesses in the area. They want to be able to choose where everything goes, to the pixel, so it's easiest to work with just html and css. Then I can upload to BitBalloon and everything works exactly as it did on my laptop. Forms work, everything gets optimized, and setting up my own domains is super simple. And it's cheap.
I could use S3 or something else, and it would be cheaper, but deploying in a half second really is useful. Everything is done right with no effort on my part other than building the site itself.
I also built a site just for fun and host it there. 750,000 page views in the last couple weeks, didn't worry for a second. http://gallerrit.com/ It has also been very easy to push updated versions with no down time.