I recently posted a web based utility that I created to allow administrators and even non-OpsMgr users to be able to trigger/schedule maintenance mode. Another really cool use for such a web based tool is that it can be configured for use through the OpsMgr console. No longer do you need to go to three different locations in the console to schedule full maintenance mode - nor do you have to leave the console and run a powershell script or external tool to configure maintenance mode.
Setting this up is a simple matter of creating a new web page view. From there, enter the URL to the maintenance mode website and, all done...now you can work with maintenance mode through the console very easily! The example shown below is a view created in the 'my workspace' node - but this could just as easily be created in the monitoring node.