Jane Straus, author of The Blue Book of Grammar and Punctuation, has put the entire contents of her book along with some other resources online for public use at GrammarBook.com.
Features:
• Confusing words, grammar rules, punctuation rules, capitalization rules, and rules for writing numbers
• Interactive quizzes and tests on grammar, punctuation, capitalization, and writing numbers
• Videos on common usage problems
• Newsletter and grammar blog
Site URL: http://www.grammarbook.com/