Vimcasts publishes regular screencasts about the Vim text editor. Episodes are kept short - typically less than 5 minutes, never more than 10. The aim is to provide something in each episode that you can take away and use.
Shell-fu is a place for storing, moderating and propagating command line tips and tricks.
All well known, but pedagogy by repetition never hurts...
Beautiful SVG representations of essential survival information
Plenty of simple renaming one liners for the whole family !
This text is a very comprehensive one-stop information resource on how you can use Unicode/UTF-8 on POSIX systems (Linux, Unix).