Is there a way to have SharePoint automatically log off users after they have been idle for a specified amount of time? I have a site that utilizes NTLM, Windows Authentication and after 30 minutes of inactivity, it is not currently logging out users. I have tried setting IIS session timeout, SharePoint session timeout, SQL connection timeout in the web.config, and nothing has worked thus yet.

Yep, you can, set the session timeout. Refer here :http://technet.microsoft.com/en-us/library/cc263527(office.12).aspx Thanks ~Uday, http://www.mstechblogs.com/sharepoint

You can set the security validation to log the user off after X minutes in the Web Applicaiton General settings in Central Administration. Please note that if the user's browser has been configured to pass credentials automatically the user will be able to log back into SharePoint without supplying a userID and password. If you are setup for an automatic login then this setting is ineffective.Paul Stork SharePoint Server MVP