Usually there's a preference somewhere to add or remove those menu extras, though not always intuitively. The padlock to lock the screen for example is in Keychain Access. (as it also has options for locking/unlocking keychains in the menulet) I THOUGHT the eject menulet was selectable in disk utility's preferences, but Disk Utility currently
doesn't have a preferences menu to select it from. Didn't it used to, long long ago?
And that Eject menulet will let you select which device to eject or open. I used it frequently when I needed to use Remote Desktop to access a headless mac pro and open its optical disk drive bay. (eject key on the keyboard was not effective over ARD) It's also useful when you would normally hit the key on the keyboard, but you have more than one optical drive attached, it will always eject the first one with the keyboard.
