How do I center images or align text via CKEditor? Can I add more functionality?
A frustration I have had with CiviCRM has been the inability to center images or align text without modifying source code.  This frustration was recently resolved by visiting 

Administer -> Customize Data and Screens -> Display Preferences -> Configure CKEditor 

At the top of that page you will notice you can customize the skin (I recommend Moono-Lisa) and to the right of that - Plugins. You can search for CKEditor plugins and add them to CKEditor. You can also customize each toolbar for CiviMail and Events - or choose to have them mirror the default.

In order to justify text - I recommend the Justify plugin and the Image2 plugin.  Now you should be able to justify text and images as you like. 

There are other plugins that provide other functionality, but do your research before adding them. the CKEditor site has explanations of each plugin.

Note: you will likely have to clear your local cache in order to see these changes.