This format might very well be the replacement for JPEG.
Here's a crude demo of various combinations of settings to show how small these files can get and still look accepable.
Currently browser do not support this format, so a javascript decoder must be used.
Hopefully this will change in the future.
You can also download the original image.
Seems really cool, doesn't it? Sadly you can probably forget about this format because of the many software patents being in the way.