http://www.nick.com/games/legend-of-korra-welcome-to-republic-city.html?xid=5KOR_LOKTu
Here is the interactive Site that Nick mentioned in the premiere press release.
The site give an extremely informative and interactive tour of the various locations of United Republic, only 3 of the Sections are open at the moment , but the other ones will be unlocked soon.
In each section you find various interactive features from clicking on characters, objects or animals and then you can find out more about them.
In the sections we have here we find out stuff like the ages of many of the Korra characters as well as little extra details about them, way too many to list. We get some interesting backstory on United republic that clearly is linking in With The Promise Comics.
NOTE/ This is USA only as it is on Nick.com, if like me you are not from America I highly recommend using http://www.tunnelbear.com/ to use the site.
