Brain pop- really good links http://www.brainpop.com
(Sample link) Fun activities - by girls....for girls. http://www.missoandfriends.com/
Great website for practicing decimal operations/concepts- 8 different games! http://www.decimalsquares.com/dsGames
Fraction website http://www.gamequarium.com/fractions.html
Fraction game http://www.visualfractions.com
Fraction game http://www.jamit.com.au/fraction-games.htm
Making Change Game http://smartboards.typepad.com/smartboard/2008/11/smartboards-and-real-change-you-can-use.html
Making Change game http://www.mrnussbaum.com/cashout/index.html