I Command You
The old days of command line interfaces seem scarce, frightening and even gone in places in this gui driven world of ours. Although, there are aspects of the command world that show itself as subtle advancements in good interface design. Take for instance Gmail and it's interface below.

Gmail, adds a few shortcut keys to navigate around the site. Use K to move up and J to move down in the list of e-mails. Hit O to open an e-mail, X to select it, # to delete it. These are subtle additions that can make a great interface even better to use. Another great example - Microsoft's Visual Studio.

We underestimate our ability to take advantage of the keyboard in most applications today. Keyboard commands often get supplemented by menus, buttons and other pieces of user interface that typically will break our train of thought. Can you imagine what it would be like if we wanted to know a method for a class in some object in Visual Studio without intellisense? Imagine how much pain we would go through if when we wanted to go to a website we had to choose from a listbox instead of typing in a url to one or searching for it.
This is why it's important to understand that users do know what they're doing and that commands aren't always the worst of things. We were always used to them in the old days, there should be no reason why they shouldn't continue to enrich our experiences today.