Revisiting a link I saved a while back, about dealing with lots of  information (reading for understanding, but also reading a lot), on Matthew Cornell's 'the experiment driven life' blog.

I'm still thinking on it, but so far I like the first, simplest method he references at the start of the article, paraphrased my way here:

Quick Reading For Understanding

read table of contents, possibly index (if simple/short index)
then start over and read
     section, chapter titles, subtitles, bold headings
then start over and read
     first line of every paragraph
then start over and read
     entire book

Aside from the deeper understanding and memory retention all the above supposedly promotes, seems to me you might also get the benefit of a higher confidence in a decision to deep-six a book before the final 'proper' reading. I mean, once you get finished reading the first line of every paragraph, you can have a fair amount of confidence in your judgement of whether the book is worth pursuing.

I wonder if there exist reading scripts that help with this for e-books (like folding editors); set the current reading level and just read, with the deeper level stuff hidden until needed.

Vim/emacs could handle it  I'm sure; I wouldn't be surprised if one or both didn't already have a mode or script for it.

From the other end of the stick, what about writing with this sort of reading in mind?
for print:

literally print the toc,
then just a listing of chapter and section titles and subtitles
then just the first line of every paragraph
then the full text

for web/pdf/anything that supports scripting:

write within a folding structure so that deeper levels are
hidden until desired/needed.

The for-print version would probably not fly very well; too much extra printing. Still, an author could assist in the process by at least using a different font or bold-face or underline the first line of each paragraph. That would make it easier for the eye to jump from one to the next.