Boot a linux kernel right inside your browser. 
This is demonstrative of the advantages of the new low-level APIs being added to JavaScript to work efficiently with binary data.<p>Fabrice uses this to implement an x86 interpreter -- it could not be done efficiently without typed arrays. However, it is still slow -- imagine what kind of advances could be made if a common bytecode was established that would be JIT'd by the JavaScript VM, and could be output directly by the emulator.<p><i>This</i> is why so many people want to see the browser execution environment offer more complete, low-level APIs instead of high-level APIs locked to HTML/CSS and legacy browser technology. Efficiently supporting high-performance, high-complexity systems such as an <i>x86 emulator</i> (or a video game, or custom font rendering, or even an application framework) absolutely require efficient low-level APIs.