http://www.eduplace.com/kids/hme/k_5/quizzes/index.html  -  Quizzes on grammar. (grades 2-5)

http://www.bbc.co.uk/schools/wordsandpictures/phonics/sandcastle/index.shtml -  Quiz on vowel phonemes. (grades 1-2)

http://www.bookadventure.org/ki/bs/ki_bs_helpfind.asp - Allows students to find books that are interesting to them by search reading level and topics.  (grades K-5) 

http://www.starfall.com/ - For beginning readers. (grades K-1)

http://www.readingrockets.org/ - Offers a wealth of strategies, lessons, and activities designed to help young children learn to read.

http://vocabulary.co.il/index_main.php - Builds vocabulary skills and test prep skills. (grades 1-5)

http://www.citationmachine.net/ - Designed to help students easily cite references for research papers. (grades 4-5)