This site has some simple little review games for the kids to do over the branches of government, checks and balances, and the executive branch
This is another nice site which covers the basic of government for kids. It was created for a Thinkquest competition.
This Congress for Kids site focuses on Ithe legislative branch.
This PBS site was created for the 2008 Election, but it still has a lot of good information!
This site offers an interactive field trip of our nation's capital.
This site has a good Washington D.C., webquest.
I really enjoy teaching social studies, and government is one of my favorite things to teach. One thing that makes it difficult though is with the spiral curriculum, it is difficult to get the kids excited about something that they have learned about already in the last two years and will learn about again for the next two years, so I am always trying to find new and interesting ways to engage them. One thing I do is that I focus on our government in Illinois. That seems to help somewhat. :)
I hope you find these worthwhile. I would love to know of any other great resources that you have used or have seen--even those that aren't websites!