I started reading aloud the City of Ember two nights ago to them, and they keep asking for more!
I have a few links for you...First is the trailer, because for us, that's what started it all!
Next, I found a lot of great activities to do with the kids on Walden Media, in the Educator's Guide section. You just need to scroll down to the City of Ember. Here you can find activities like "Building Ember" by building a tower with uncooked spaghetti and marshmallows, or "Living Underground" where you need to draw a plan for your own underground city, or a map activity in "Navigating Ember", or a look at the real 2003 blackout, or building a light bulb or a hydro power generator...I think you get the idea...and there are more on the site!
Last, here is the link for Wikipedia for The City of Ember.