Skype for Slack - Move your slack discussions to a group skype call
RBTray - Allows almost any program to be minimized to the system tray by right clicking its minimize button.
Calls on Slack - Make voice calls in Slack
4t Tray Minimizer - 4t Tray Minimizer Free/Pro - Minimize Outlook, Internet Explorer, Firefox, Chrome and any other applications to the system tray!
Pingly - Your communication hub — Email, text & voice in one app
Minime - Minime is a tool that allows you to minimize applications to the system tray using a simple hotkey.