Advanced Wifi Information
Never boot up terminal for basic information again. Option-clicking on the wifi status bar item reveals an extended list of essential information relating to your local network. This is by far the easiest way to get information about your network on OSX. It makes sense for there to exist an easy way to check your MAC/IP address, but there's even a reminder of the address of your router (something I always forget).
Sound Device Shortcuts
Previously, to check/change audio input/output devices on your mac you were probably booting up System Preferences and navigating to the Sound menu. It turns out that there was a shortcut sitting right in front of you: option-clicking on the audio menu item is a quick way to see the status of your connected devices, and to switch between them.
Advanced Bluetooth Menu
You may have noticed a pattern here: option-click does some cool stuff to the status bar. This one has probably never served a practical purpose to anybody, but option-clicking on the bluetooth menu item shows you the protocol version your computer's using, and its hardware address.
I'm somebody who locks their macbook habitually. I've stuck a shortcut to lock on my bottom-left hotcorner, but other people are thrown off by my extensive hortcorner use. Turns out there's another way: use spotlight to boot up Keychain Access, and in its preferences, there's an option to add a lock item to the status bar.
And before you try it: no, option-clicking does not do anything in this case.
Emoji & Symbols
This may be revolutionary to you: in the keyboard preferences of your mac, there's an option to add an emoji and symbols shortcut to the status bar. The keyboard shortcut ⌃⌘SPACE also works to open upt his menu.
Color Picker [3rd Party]
This is a third party app that I use more than daily. Color picker is truly a necessity for any developer or designer. It adds a nice-looking status bar item, and a shortcut (by default ⇧⌘M) which at any time can instantly bring forth a beautiful color picker with a magnifying glass.
Monity [3rd Party] [Widget]
One more third party app I have to recommend to nerds; I hate that it cost me $8, but I love not booting up Activity Monitor every time my mac is running a little slow. I'm somebody who frequently checks how their RAM is going (some scanner driver software I use has a memory leak 😌), so Monity has really justified the existence of the widgets dashboard for me. Its design is flawless and from what I can tell, it's bug free.