How do I add icons to my menu bar? I would like to know how I could add a USB eject button or battery power indicator to my menu bar on Mac OS X. I remember going into my Macintosh hard drive but I can't remember which folder to find it in. I know to drag out an item from the menu bar by pressing the command key and at the same time dragging the icon onto the desktop, but how do you add icons to it?
I'm assuming by "desktop toolbar", you mean the bar at the top of the screen (properly called the menu bar), please correct me if I've made the wrong assumption.

You can add the eject item by opening /System/Library/CoreServices/Menu Extras/ in Finder, and double-clicking the file named Eject.menu. It should appear in the menu bar right away.

To add the battery indicator, open the Energy Saver pane of System Preferences, and check the Show battery status in menu bar box, near the bottom of the window.