HTML 5 is the new W3C definition for HTML and is likely to represent the direction the Internet will look when people find the next killer applications that run on it.
There are widespread "publicly available" encoding functions, such as a tag <video>, but I wonder what low-level encoding tricks have been found so far, which may be important, useful, interesting, or all of the above.
Some examples that I have encountered so far:
Drag and drop events that control data transfer - for example:
document.addEventListener("dragstart", function(event)
{
event.dataTransfer.setData("image/png", slides.imageRep());
event.dataTransfer.setData("slides", slides.serializedRep());
}, false)
Two-dimensional and three-dimensional graphics through the expansion of the element <canvas>.
Context-oriented html blocks
( - obselecense <applet> <marquee> - woohoo!)
<ruby>
, , <progress> - .
- ? , - -?