Interestingly, I've just realized that I can use bookmarks at the site to refer to places in the book, and keep the book free of bookmarks/constant travel/etc., thereby ensuring the value of my investment, as it were.
That plus the other tangibles mentioned at the site as to why the book's worth the money -- can't curl up by the fireplace with an LCD. (Well, you can, but it's not cozy.) Books aren't subject to power failures, etc.
I'm planning to actually build a Mason site, if I can swing it somewheres. I need to find out if either of my free hosting locations currently has Mason and mod_perl installed, so I need to figure out a way to test it without bugging the admins, if possible.