Use this link to review your understanding of subjects and predicates.
http://languagearts.pppst.com/subjects-predicates.html
http://www.softschools.com/quizzes/grammar/
This site will help you choose books that are similar to ones you have read and liked. It can also help you choose books that are appropriate for your reading level. Just enter the title or author in when it prompts you and select the option to find similar books by clicking on "Book Alike".
http://www.scholastic.com/bookwizard/
This site offers extra games, printable worksheets, quizzes and extra practice for Grammar Skills.
http://languagearts.pppst.com/grammar.html