You can set the duration of your webclient login in any web browser, using either a timer countdown or a specific logout time. This way, if you forget to logout at the end of a shift, you will not leave your chat service falsely online for a long period of time.
If you use Chrome, you can also use a browser plugin to detect browser activity and automatically logout.
If you realize you've left yourself logged in on a computer you cannot physically access and did not enable auto-logout, you can opt yourself out of your queues. Sign into the webclient from another location and opt yourself out using the regular queue selection box. This will opt you out of your queues from all locations no matter what software client you are using. Phew! Then, logout as usual. You'll be able to opt yourself back in when it's time for your next shift. Also, an administrator can still prevent online users from keeping a service falsely online
You'll see the auto-logout option at the bottom of the "Choose Staffing Assignments" dialog box that shows up at each new login. You can set any number of hours and/or minutes. When that time has elapsed, you will be presented with a box that lets you know of the impending logout and lets you extend the time if needed. If you don't respond to that auto-logout prompt, you are completely signed out in a minute.