The all time favourite: Drum Roll Please........Club Penguin
http://play.clubpenguin.com/index.php?lang=en

Typing Practice/ Typing Games
http://funschool.kaboose.com/gamesFiles/flash/kaboose/spidertyper/spidertyper.swf

Check out Kids Discover for some fun internet activities.
http://www.kidsdiscover.com/kids-online-games

If you like animals and all things science you will certainly have a blast hanging out on this cite learning cool facts and playing interesting games.
http://www.kidsknowit.com/

Do I hear Social Studies?  Social Studies anyone?
http://www.socialstudiesforkids.com/funfacts/funfacts.htm

More Keyboarding fun
http://www.tvokids.com/framesets/play.html?game=222

Could English possibly be ridiculously fun?  With this website it certainly is. 
http://www.earobics.com/gamegoo/gooey.html

Interested in Science Experiments.  This website has a long list of things that you can try at home.
http://easyscienceactivities.blogspot.com/

Ready for a little of everything?  Check out this site for a variety of games
http://www.mrnussbaum.com/