As long as AutoMute is running, whenever your Mac goes to sleep, wakes up, or a pair of headphones gets disconnected - the sound is automatically muted.
https://itunes.apple.com/us/app/automute-preventing-awkward-situations/id1118136179?mt=12
Don't let your Mac fall asleep. Extremely useful if you are using your laptop to present during a meeting.
http://lightheadsw.com/caffeine/
Move, zoom, and snap windows to edges and pre-defined layouts. Support for automatic adjustment to display setup changes. Useful if you like to keep an orderly screen while you are working.
Cinch allows you to precisely resize a window simply by dragging to the left, right, or top screen edge.
http://www.irradiatedsoftware.com/cinch/
The only terminal console you'll ever want to use on macOS.
Fantastic cross-platform diff and merge utility.
GeekTool is a macOS application that lets you customize your desktop with great flexibility. There are four modules available that you can use for different types of information.
https://www.tynsoe.org/v2/geektool/
Lingon can start an app, a script or run a command automatically whenever you want it to. You can schedule it to run at a specific time, regularly or when something special happens.
https://www.peterborgapps.com/lingon/
SSH Tunnel Manager is a macOS application to manage your SSH tunnels. If you don't know what that is, quite honestly, maybe you don't need SSH Tunnel Manager, but if you appreciate the power of connecting together two networks using the SSH protocol, then STM is for you.
https://www.tynsoe.org/v2/stm/
Convenient wifi SSID scan from the command line.
$ ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport ~/bin/airport
$ airport -s
SSID BSSID RSSI CHANNEL HT CC SECURITY (auth/unicast/group)
MyWifi 90:84:0d:c3:b2:a1 -74 1 Y US WPA2 (PSK/TKIP/TKIP)
BTOZone 00:de:ad:be:ef:a1 -82 6 Y US WEP
MyWifi 00:24:36:c3:b2:a1 -27 11 Y US WPA (PSK/TKIP/TKIP)
MYFI 00:18:01:c3:b2:a1 -70 11 N US WEP
MYFI 5G 90:84:0d:c3:b2:a1 -87 36,+1 Y US WPA2 (PSK/AES,TKIP/TKIP)
MYFI 5G 00:24:36:c3:b2:a1 -35 157,+1 Y US WPA2 (PSK/AES,TKIP/TKIP)networksetupcaffeinateopenopendiffqlmanagescutilsystemsetuptextutil