Gmail can remotely sign you out from all your signed in sessions.

Have you ever forgot to sign out of your Gmail account and realize it later? This would be a serious issue if you are using public computers. But Gmail has you covered. You can use Gmail’s capabilities to remotely sign-out from all your signed-in sessions.

On any Gmail page scroll down to the bottom of the page where you can see your account usage information in terms of size. Just below that you should be able to see your sign-in/sign-out activities as well. If you are signed into your Gmail account from multiple place you should be able to see a similar notification like above which tells you that the account is open in other locations as well. Click on the "Details" link to find out more information about the activities.

As you can see above, the dialog lists all concurrent sessions along with the last 5 activities. In between these 2 information you can find a button "Sign out all other sessions". You can use this button to sign out from all other signed-in sessions.

If you realize that you didn’t sign-out of your Gmail account you can sign-in again into your Gmail account and use the "Sign out all other sessions" button to sign-out from all the signed-in sessions. This would come in real handy when you realize that you forgot to sign out of your Gmail account from a public computer. Keep this information in mind. Who knows it might come in handy.