A free Ubuntu Pocket Guide authored by Keir Thomas has been launched recently. (Thanks to Tectonic) Excerpt:
Keir Thomas, author of numerous Linux how-to books as well as Ubuntu-specific guides, has released a new book called Ubuntu Pocket Guide. The compact 166-page guide to using Linux is available in both printed form as well as a free PDF download.
Thomas says that “people are encouraged to share the PDF Edition file with friends, and even upload it to file-sharing networks. The PDF edition is exactly the same as the print edition.”