Get a Free Book of Windows 7 Shortcuts
Regular Hassle-Free PC readers know of my fondness for keyboard shortcuts, which can really save time (and cut down on accidental mouse-clicks in the wrong spot, a problem that plagues every user from time to time).
Windows 7 offers some 200 shortcuts, and each and every one of them is identified in The Complete Windows 7 Shortcuts eBook.
This 43-page guide covers not only the OS, but also apps like Calculator, WordPad, Windows Media Player, and Internet Explorer. It's arguably the most comprehensive keyboard-shortcut guide I've ever seen.
This excellent resource is provided in both PDF and XPS formats (this Zip file contains both). Even better, it's free of charge!