I try to save paper these days by reviewing manuscripts via PDFs on my computer or my tablet. It also makes it easier to read stuff while traveling--both to read on a plan and to carry less paper around.
The biggest challenge in doing this is the habit/standard of people putting their tables/figures at the back of the document and having endnotes and not footnotes. I know most of the blame for this goes to journals which require such formatting, although that is changing (thanks Dan at ISQ).
So, I am going to be annoying and ask my students/friends who give me stuff to read to format it the way I want it--intext figures/tables and footnotes. Sorry, but the line is drawn here and no further.