Some updating line charts in d3

There are so many lovely d3 demos... but I think this might be more due to the creativity and stubbornness of the people who have chosen to use d3 than because of some innate quality of the library.
(d3 is a charting library, that claims it is not a charting library; instead it likes to see itself as an alternative to JQuery, I think.)

As a case in point, there is this page showing three beautiful examples:
   http://bost.ocks.org/mike/path/

In particular scroll down to the bottom and it is tracking how much scrolling you've done on the page, with the time on the x-axis. But the script for this cleverness is about 110 lines. And it is quite opaque. To put that comment in context I've read the O'Reilly d3 book cover-to-cover, then played with every d3 example in the book.

By the way, another example of scrolling charts, this one with multiple charts overlaid: http://lyngbaek.com/real-time-stream-graph.html

Here is a similar chart done in Rickshaw (which is another library built on top of d3): http://code.shutterstock.com/rickshaw/examples/fixed.html

And another example done in Rickshaw, that is quite heavy-duty: http://code.shutterstock.com/rickshaw/examples/extensions.html