- from the taint.org blog / Geeking with Greg: Introduction to Information Retrieval – very interesting with contributions from real practitioners
- from the all about linux blog: Ubuntu Pocket Guide and Reference
- from the all about linux blog: Open Source E-Books for Linux (a large collection of them)
- A collection of usability guides for GUI designers
- from the Lightweight Linux blog: Linux Kernel in a Nutshell
- from the Lightweight Linux blog: The Linux Cookbook: Tips and Techniques for Everyday Use
- Wikipedia: The Missing Manual – I already mentioned this, but wanted to have a complete list in a central location
Image taken from ailatan's photostream with permission.