window.history.pushState()
In HTML5 there is new, unprecedented access to alter the URL shown in the address-bar of the browser.
I guess it can be used for something good, and that I am just a grumpy old man.
But let's try an example. Click a URL:
And then check out the address-bar. Sweet, huh?
Man, that can be used to shoot yourself in the foot. Like, say, implementing page-loads within Javascript, because, y'now, browsers are really bad at loading pages... Viz pjax.
Don't. Break. The. Web. ⊗