I am in the middle of that honeymoon you get starting a new app. Every new feature seems tobe just 50 lines of code away, there is no legacy code (in fact, you are creating that legacy code), and you learn new tricks all the time.
So, I did a new feature today.
A day or two ago, my editor started showing a yellow bar highlighting the current line.
But then I though... wouldn't it be more useful to have a similar bar following you in the PDF?
That way, when you are on a given line, you can immediately see where you are in the output. Neat, right?
Here is a video showing it:
Sadly it's not perfect, and probably never will be because of docutils limitations, but it's pretty nice!