On-line grammar work

The Grammar Aquarium Very orderly list of typical areas of confusion, offering explanations, online exercises and paper exercises.
ESL Blues Remarkably complete site - it provides you with evaluation tests that will show your weaker points and indicate useful tutorials and/or exercises at all levels from beginners to advanced level learners
Better English Starting page for list of grammar exercises of all sorts in Java (Hotpot) especially the "miscellaneous sectiion -
Geocities A database of vocabulary/grammar quizzes for English written in Javascript (hotpot) - at beginner, intermediate and advanced levels
Gramlinks A rich source of explanation and exercises about English grammar - intended primarily for francophones
Politeness quizz in English  
Hypertext English Language Practice These pages provide information and practice exercises about the grammar and vocabulary of English . Pages created by Richard Side and The Eckersley School of English At the moment, there are pages on these areas: phrasal verbs , relative clauses and pronouns, a grammar quiz animal idioms
Grammar Hunt Grammar hunt: this is a good starting point to find exercises about (at least) the following items: 1.Adjectives 2.Adverbs 3.Agreement 4.Articles 5.Idioms and Phrasal Verbs 6.Linking Words and Phrases 7.Modal Verbs 8.Miscellaneous 9.Nouns 10.Passive 11.Prepositions 12.Pronouns 13.Punctuation 14.Question Forms 15.Register 16.Sentence Structure 17.Spelling 18.Style 19.Verb Tenses 20.Verb Patterns: Gerunds, Infinitives and Participles etc 21.Word Choice 22.Word Order
http://www.lang.uluc.edu/r-li5/esl learning English online, with sounds, lessons, a quiz and more

Online vocabulary work

Over 200 short vocabulary tests classified by level (easy to difficult) - answers and comments provided, as well as a print version
Illustrated vocabulary Provides practice on elementary vocabulary of daily life in the form of illustrated tests with correction
Geocities A database of vocabulary/grammar quizzes for English written in Javascript (hotpot) - at beginner, intermediate and advanced levels
Hypertext English Language Practice These pages provide information and practice exercises about the grammar and vocabulary of English . Pages created by Richard Side and The Eckersley School of English At the moment, there are pages on these areas: phrasal verbs , relative clauses and pronouns, a grammar quiz animal idioms

Online listening practice

ESL Lab Listening exercises to train your ability to understand oral English

Online pronunciation work

http://www.unil.ch/ling/phonetique/api-eng.html complete course about the international phonetic alphabet
Fonetiks provides pronunciation practice

Online writing practice

Junket Studies This site is a concise guide to some of the most commonly violated rules of writing, grammar, and punctuation. It is intended for all writers as an aid in the learning and refining of writing skills. Explore each of the rules to see examples of its application, and use the references to find additional explanations and examples on the Web or in print. Look up grammatical terms in the glossary. For a wider variety of information, check related FAQs and other writing resources. Also, click on the Word of the Day until you've learned a few new words.

Ruth Vilmi's writing course

a complete writing course