Command Line Cheat Sheet for Mac and Linux. I know these, but always good to have on hand!
#MySQL Cheat Sheet by Example
The Art of Unix Programming
The Linux Terminal offers you linux tutorials, wallpapers, free bash scripts, unix programming, tips & tricks, hacker & security news, linux distributions & video how to's.
Unix/Linux Command Reference - #Linux
C++ GUIDE QuickStudy® $4.95 Ultimate guide to C++ programming language. Guide assumes that all readers have a general understanding of programming languages, and an understanding of the PC/Wintel environment. #C++ #Programming #Computer
Precision Series Unix Programming Environment
linux admin quick reference
Linux kernel diagram ( very technical stuff for future reference )