Useful Linux kernel resources

Linux Device Drivers book: A must-have book for people creating device drivers for the Linux kernel! Now available in a single PDF file.
Linux Kernel in a Nutshell book: Configuring, building and managing Linux kernel sources, by Greg Kroah Hartman. Now available in a single PDF file.
Elixir Cross Referencer: Our webserver allowing to explore the sources of the Linux kernel, and other other useful projects.