linux basic commands

Every body know, that when you are using Linux, you have to use commands to do your stuffs.
But now-a-days most of the new distros are very polished and providing more GUI interface to perform the stuffs, but still we need commands for more than GUI for our work. Preferably i like to use bash(terminal) for most of the stuffs.
So if you want to do your stuffs by using commands. there are some websites providing these useful materials:

oreillynet
An A-Z Index of the Bash command line for Linux.

ANL