Offer offline documentation in more formats
While the offline viewing option is great, PDF's "baked in" page format makes reading on mobile devices very cumbersome. I suggest offering downloads in open ePub format for easy reading on mobile devices -- allowing for text reflow, text and margin adjustment, color themes, etc.
Cavan Watson commented
Just read about Visual Studio eBooks, available from inside VS...
Shame that you are not publishing this off line content in the Apple iBook Store, be good to have this literature available on my iPad for the commute.
Chad Simmons commented
Add the Microsoft Word format as an offline viewing / download option.
There have been several suggestions for downloading and accessing MS-DOCS content offline. The PDF capability is a great start.
Access to additional formats such as ePub, Mobi, and others could be very useful as well.