What features of Mavericks are beneficial to you?

This question serves to share and collect the enhancements that make a large difference to how you use your Mac.

Please post one feature per answer. Please also check to see if your answer has already been posted - duplicate answers will be deleted. To search answers for this question use inquestion:this (directly from the question page) in addition to your search terms in the search box in the upper right hand corner of this page.

The best answers will not only list a feature, but provide details on how to configure that feature, and provide an image of how to use the feature to be more efficient or effective with Mavericks.

The overhaul of the virtual memory system makes it clear that memory pressure is the primary factor to track and not how many free pages, inactive pages or overall virtual memory is allocated.

The bottom panel is invaluable for diagnosing a slow machine and knowing whether to rule out memory contention as a cause of the slowness. After running your Mac for a week, you should reach a nice steady state like shown above and can know if adding more RAM or adjusting the programs you run will affect performance.

With a text field active, Control ⌃ + Command ⌘ + Space opens a characters panel including Emojis.

The energy consumption view that collects 8 hours of history and graphs the charge level in your battery as well as showing each process that drained measurable amounts of energy is going to make squeezing extra productivity out of one charge much easier.

Not only will developers (I'm looking at you Dropbox) know that they have to be better stewards of battery life, it makes it easy to see which apps support App Nap and even that a program that is quit now was responsible for using energy in the past 8 hours. This tool provides actionable information for users to better manage their experience when away from wall power on a portable Mac.

This detail is quite hidden inside Activity Monitor, but Apple does expose the biggest users of energy in the menu bar for apps using significant energy.

Secret Wallpapers

OS X ships with a bunch of really cool sample photos that are not normally available for use as desktop backgrounds.

Previously in OS X 10.8 Mountain Lion, these were located at:

/System/Library/Frameworks/ScreenSaver.Framework/Versions/A/Resources/Default Collections/

In OS X 10.9 Mavericks, they’re now located at

/Library/Screen Savers/Default Collections/

Here's how to get them:

• from Finder, use the menu Go → Go to Folder… (or hit ⌘⇧G) and paste in: /Library/Screen Savers/Default Collections/

You should see 4 folders, and inside them you’ll find lots of really cool Wallpapers:

Bring Your Home Folder's Library Back with One Checkbox in Mavericks:

Apple decided to hide the Library from its users in recent OS X updates, but in Mavericks you can now change that with a simple checkbox.

In the past you had to enter a Terminal command with every little system update:

chflags nohidden ~/Library

With OS X Mavericks, you can just navigate to your home folder, press Command+J to bring up the folder settings, and check the box next to "Show Library Folder" instead.