Starfall http://www.starfall.com/
North Pole games http://www.northpole.com/Clubhouse/Games/
Santa's Secret Village http://www.northpole.com/Overview/Kid.html
Dr. Seuss Concentration Game http://www.seussville.com/games/concentration/
Clifford Concentration (finding words with the same middle sound) http://teacher.scholastic.com/clifford1/flash/concentration/
Match the fruit concentration game http://tcastle.com/games/conc/concentration.html