Basic Unix References
Unix Tutorials:
University of Leeds: "Getting Started with the UNIX Operating System"
The Linux Knowledge Base and Tutorial: "The place where you learn Linux"
Unix References:
Computer Hope Unix/Linux Reference
(Includes a quick reference for quite a number of commands.)
Man Pages:
How to read Man pages
Editors:
vim Commands Cheat Sheet
University of Leeds: "Getting Started with the Emacs Screen Editor"