You don't need Photoshop or some other advanced piece of software to resize a large number of images at once. You can use Microsoft Office Picture Manager which is part of the Office suite.
If you activated the new Inbox Tabs then after a while you find yourself not liking them that much and would like you old priority inbox back, this is what you need to do.
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.