Mountain Lion enables you to set notification alerts to remind you of upcoming birthdays, tasks, meetings and other important events you might have in your calendar.
If you manage a Facebook Page there is a very useful feature you might have missed. You can schedule your posts in advance or you can even date them back down on the Page timeline.
In case you just upgraded your iOS powered device to iO7 or any other version and now this device runs slower than it used to, this resetting of the device procedure might speed things up.