TAKS practice http://www.tea.state.tx.us/student.assessment/resources/online/2006/grade6/read/6reading.htm
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
http://www.iknowthat.com
http://www.gamequarium.com
http://www.internet4classrooms.com/brain_teasers.htm
http://www.spellingcity.com/