Windows only: Free, lightweight application RBTray minimizes any app to your system tray. Once it's running, you can tray your windows in a couple of ways: You can either right-click the bottom-right corner of the minimise button to instantly send the app to the system tray, or you can right-click anywhere on the title bar and select Minimize in tray from the context menu (which also offers Always on top and a useless My size feature). The app doesn't require any installation, so you can also toss it on your thumb drive and take it with you. Even better, RBTray used a meager 380KB of RAM on my system. RBTray is a free download, Windows only. For more alternatives, check out previously mentioned TrayEverything or Trayconizer.