The Blender Manual is available online as a Wiki, in which the editors continually collaborate on improving the content. This is nice if you're a broadband user but if you're not always connected then you used to be out of luck. Not anymore!
Wisivenita has compiled the manual into a Windows Help file that contains all the texts, pages and most of the hyperlinks. It's a bit of a hefty download at 26.5MB but even if you're a modem user you can probably find a place where you can download it and put it on a memory stick for use at home.
If you're not a Windows user: don't worry. You can use these help files on other platforms, too, but you'll need to download a (free) .chm reader. For OS X, there's Chmox. For Linux, you can use Gnome's Chm, KDE's Kchm (both are included in those Desktop environments I think), or Xchm. There are tools available for Pocket PC as well.
I just hope that this initiative won't be a one-off and that this version will be updated regularly and that it gets a prominent place on the Wiki.
Download it, keep it on your desktop and don't worry about not being online anymore when you need the manual.
You can download it from these mirrors:
note: to download from rapidshare, you must scroll down and click free then wait.