As a command line junky myself, I found this article quite pleasing.

I would like to see more applications provide a CLI as an alternative (or supplement) to their WIMP interfaces.

Better yet - the CLI would be integral to the OS. Every GUI application would expose hooks to allow control via a command line.

On my mac, if I could press a single key to have a command line window appear (knowing the os x designers it would more likely morph out of my background image). In the command line I would have access to several global commands to do things like list my applications (or list running apps, recently run apps, favourites, etc), switch to an application, etc. Once I switch to an application my vocabulary of commands would also switch to now include commands specific to that application. If I switched to the mail application I could enter a command to send a new email message or I could search for messages from a specific email address etc. Since global commands are still available to me I could then switch to iTunes. My vocabulary would switch as well. I could then enter commands to search for a song by a favourite artist or to start playing a specified playlist.

Where appropriate the control would switch from the command line back to the GUI automatically. With mail application selected, if I entered the command "new email to jim" control should shift back to the mail application with a new message window already open. Clicking send on that window should direct me back to the command line window.

I haven't played with AppleScript at all but as more and more applications become scriptable... maybe having a sort of script console accessible via a hotkey would provide much of what I describe. For applications that aren't scriptable, modules for the console could be written to allow scripting via "GUI Scripting".