How Can I Tell Which Apps Are Using The Most Power On My Mac?

This is a new feature in OS X Mavericks. To see which apps are using significant energy, click on the battery/power icon in your menu bar. If there are any apps that are particularly resource intensive, you will see them listed under a heading that reads "Apps Using Significant Energy". Clicking on that app within the menu bar will then take you to the Activity Monitor app to see even more information. If no apps show under the list then everything is running at a normal level.