MonitorControl - Control your external monitor brightness&volume on your Mac
Dropzone - If you want your file uploads to work even without JavaScript, you can include an element with the class fallback that dropzone will remove if the browser is supported.
Lunar.fyi - Control monitor brightness, adapt using the ambient light sensor, adjust volume, switch inputs and turn off displays without fiddling with clunky buttons.
Dropover - Mac app for easier drag & drop
Screens - GNU Screen.
Unclutter - Unclutter is an app that is designed to help Mac users bring order to their desktop. Among other features, this powerful piece of software provides quick access to a user's notepad and clipboard.