I like Terminal. The power you have in such a little application. Anyway, I stumbled across this cool command while smashing my hands on the keyboard. In its simplicity it will list every single command available on your system. It will very between system to system, with the amount of commands available.
Open up Terminal and press and and hold Escape you should get a message saying “Display all 1420 possibilities? (y or n)” you then have the choice to press Y for yes or N or no. A second later all of the commands will be displayed. Not all at once, but in alphabetical order.
You then press enter to cycle through one line at a time. It will take a while to go through every line but you can find some cool commands. If you want to exit out of the list half way through press backspace (delete on a MacBook/Pro).
A very cool little tip and lets you find some cool commands. Not every command will work, and you should be very careful as some commands you will see can damage your system (rm comes to mind). If you are bored one day you now have every command available to you. It of course, wont show you commands within applications, for instance in emacs or vim.