1. Online Dictionaries
(with visual and audio/pronunciation features, also with ESL learner features)
Merriam-Webster online dictionary, http://www.m-w.com/ , VisuWords, http://www.visuwords.com/ and Thefreedictionary: http://www.thefreedictionary.com/lookup.htm
2. Grammar Girl: wonderful free podcasts for anyone interested in improving writing skills in English:
3. Online Essay Map: great tool for students who can not organise ideas in paragraphs or don't know how to write a topic sentence:
4. Free online Puzzle and crossword makers, great fun tools to improve students' spelling and vocabulary: http://www.puzzlemaker.com/ (a Web-based service, with a variety of puzzles to choose from (Letter Tiles, Crosswords, Fallen Phrases).
Kelly's Multiple Choice HTML Quiz Generator, http://a4esl.org/q/h/help/write-mc.html (which may be used to generate interactive self-study quizzes, where the sample questions are replaced with one's own.).
5. Media Sharing Tools:
Slideshare - the world's largest community for sharing power point presentations on the web
TeacherTube – an online community for sharing instructional videos
Just demonstrate the students how to use them and then they will take over the classroom! How about your list of must-have blogging tools for teachers and students?