Better English resources and exercises: Online diagnostic / assessment tests

Test your English now (vocabulary, grammar, listening and reading (cloze test)

Free online, interactive exercises in grammar, vocabulary and discourse, from Language Project (approved by the British Council)

Elementary English Practice Exercises
Intermediate English Practice Exercises
Advanced English Practice Exercises

Free Online TOEFL, English and Multi-Language Vocabulary Test, from FreeTOEFL.net

Designed for multi-language vocabulary tests (Chinese, Spanish, Turkish, etc) and for English exams like TOEFL, iBT, GRE, SAT and TOEIC

Online Assessment Tests, from World English

Diagnostic Grammar Test
English Grammar Placement Test
English Language Assessment Test
Online English Assessment Tests

Diagnostic tests / Assessment tests on English grammar, from http://www.english-at-home.com/

Assessment Tests, from Churchill House School of English Language

Elementary Level
Intermediate Level
Upper-Intermediate Level (FCE)
Advanced Level (CAE)

Free online practice tests for learners of English, from Exam English (IELTS, TOEFL, TOEIC, Cambridge ESOL, LTE and others; also available in French and Spanish)

International House Bristol offers hundreds of free online, interactive exercises in grammar, vocabulary and phrases (elementary level for A2 to B1 on the Common European Framework, intermediate for B1 to B2 CEF, advanced for C1 to C2 CEF), useful expressions and Cambridge ESOL exercises with optional time limit for FCE (First Certificate in English), CAE (Certificate of Advanced English) and CPE (Certificate of Proficiency in English).

Free resources for teachers (lesson plans, printables, worksheets)

Sites For Teachers (Lesson Plans, Worksheets, Activities, Clip Art in subjects like Reading, Mathematics, Science, Social Studies and Writing)
WritingFix (a global resource for Writing teachers with hundreds of free interactive lessons and quality resources for classrooms where writing is taught, not just assigned; with interactive writing prompts and lessons for teachers, students and writers)

Ultimate Top 100 Kids Sites (for children, teens, parents, and teachers, with links to fun, games, education, coloring, poetry, stories, cartoons, worksheet creator or generator, game makers, printables wizard and on-line teaching materials makers with images)

ESL Kids Lab for English teaching and learning.
MES-English.com by Mark Cox (free printables for teachers of young learners)
ESL Tower (printable grammar and vocabulary exercises to make the lives of English teachers very easy)
ESL Printables, a website where English language teachers exchange resources like worksheets, lesson plans, activities, etc.
ESL Galaxy offers over 2,368 free printable worksheets for ESL lesson plans and ESL Activities and there are more additions every other day

Be a better writer or editor through StyleWriter 4

StyleWriter 4 checks 10,000 words in 12 seconds for hundreds of style and English usage issues like wordy and complex sentences, passive voice, nominalization, jargon, clichés, readability, spelling, etc. StyleWriter 4 graphs your style and sentence variety, and identifies your writing habits to give an instant view of your writing. You can learn, for example, the writing style of Newsweek, Time, The Economist, and Scientific American.

StyleWriter 4 can be used by educators, students, and professionals in various fields — business, law, social or physical science, medicine, nursing, engineering, public relations, human resources, journalism, accounting, etc. It comes with three versions: USA, UK, and Australian. Download your free 14-day trial copy now.

Miscellaneous resources