Game Aquarium http://www.gamequarium.com/placevalue.html
Lots of fun Place Value Games http://www.free-training-tutorial.com/place-value-games.html
You can read real big numbers
http://www.mathcats.com/explore/reallybignumbers.html
Practice writing and spelling the word form of numbers on Cookie Dough Checks http://www.funbrain.com/cgi-bin/nw.cgi?A1=s&A2=1000&A3=1&A12=0
Play Place Value Golf http://www.toonuniversity.com/flash.asp?err=496&engine=5
Take My Number – Get help figuring out the value of each digit http://www.webmath.com/k8placevalue.html
Place Value Movie http://www.linkslearning.org/Kids/1_Math/2_Illustrated_Lessons/3_Place_Value/
Writing words from word form to standard form http://www.321know.com/g31e_px1.htm
Greater and Less than http://media.emgames.com/emgames/demosite/playdemo.html?activity=M2A050&activitytype=dcr
Flash Cards http://www.aplusmath.com/Flashcards/
Addition, Subtraction and Multiplication Games/Click on the 3 rd Grade link for more. http://www.aplusmath.com/games/matho/AddMatho.htm
Addition and many other skills/ click on 3 rd Grade http://www.kidsnumbers.com/addition.php
pppst Lots of addition activities http://math.pppst.com/addition.html
Lots of Math Games Cool Math for Kids http://math.pppst.com/addition.html