"Literary devices and techniques?" Do you mean... hyperlinking? Because there's nothing else that's been done online that wasn't done previously in other mediums.
http://faculty.vassar.edu/mijoyce/
http://en.wikipedia.org/wiki/Afternoon:_a_story
I think you could consider this a use of hyperlinking before the web. And if you count "As We May Think", then it is a use way before the web.
It is certainly very different from a usual novel. For starters you have no idea how long it is. Hyperlinks aren't highlighted as we've come to expect and so I have to admit that I was doing some Myst-style random clicking at times. You'll often get back to the same paragraph but through a different path, these paragraphs are usually written in such a way that they would make sense by any path that you'd arrived at them.