Constitution Day

http://interactive.billofrightsinstitute.org/bri-flash-template.html - Interactive Bill of Rights (nice!)
http://www.constitutioncenter.org/BillOfRightsGame/ - Missing Bill of Rights game
http://www.annenbergclassroom.org/Default.aspx -Annenberg Classroom - Constitution Day Resources
http://www.constitutionfacts.com/ - Constitution Day facts and activities
http://cfbstaff.cfbisd.edu/davidj/Special%20Events/Constitution%20Day/constitution_day.htm - Large selection of resources/activities
http://www.texaslre.org/branches_game.html - Branches of the Government game

Government

http://www.govspot.com/features/kids.htm - Government for Kids
http://bensguide.gpo.gov/3-5/index.html - Ben's Guide to U.S. Government
http://www.treas.gov/kids/ - U.S. Treasury's Government Websites for Kids
http://www.hud.gov/kids/field1.html - Animated Tour of a City Hall
http://teachers.net/lessons/posts/1636.html - Branches of the Government windsock activity