"Your friendly guide to the world of grammar, punctuation, usage, and fun developments in the English language." A good "writing" blog to follow - useful for all sorts of tips on using English.
"This is an editing and grammar checking tool. It checks dozens of areas including:Passive verbs; Overused phrases; Vague phrasing; Cliches; Punctuation; Hyphens. It also checks for plagiarism and is great for teaching students about plagiarism, how to avoid it and how easily it's detected nowadays. In addition to correcting grammatical errors, it also provides tips and explanations for students to improve their writing."