Terminal
AppleScript
Automator

Most of the links on this page end up finding their way to free tutorials (some video tutorials). Some got to companies that offer some free and others for a fee. Many require some (free) software. Here are some links on where to get them: Quicktime, VLC, Flash, or Stuffit Expander.

There us another great source for turtorials: Lynda.com. You pay a monthly subscription and have 24/7 access to their training videos online. They also have apps for the iPhone and iPad. Not all subjects are covered. Their focus is less on basic and more on advanced.