These websites provide resources for multiple language subjects such as grammar, vocabulary, reading, spelling, etc.
Adele's ESL Corner - Easy Level
Adele's ESL Corner - Medium Level
My English Pages.com - Grammar, vocabulary, speaking, reading, listening and writing
USA Learns - Reading, writing, listening, speaking, vocabulary, and grammar. Click here for a video describing how the courses work. Originaly designed for independent learning it can be easily used with a tutor for beginner and intermediate levels. The First English Course is for beginners, the Second English Course is for intermediate-level English language learners and the Practice English and Reading course is extended practice for intermediate-level learners. The courses use media such as video, audio, animation, text and images. Activities include reading, listening, comprehension questions and writing prompts.
English Language Centre (University of Victoria) - Reading, grammar and vocabulary exercises for upper beginner (Level 200), lower intermediate (Level 330), intermediate (Level 410), upper intermediate (Level 490) and advanced (Level 570) Learners
AgendaWeb.org - Focuses on exercises, activities and worksheets.
Excellent ESL 4U - Conversations, listening, reading vocabulary and writing.
ESL Lounge - Grammar, reading, listening, vocabulary and pronunciation
5 Minute English - Grammar, reading, vocabulary, listening, pronunciation and slang/Idioms
isl Collective - Worksheets, worksheets, worksheets! Tens of thousands of downloadable worksheets on many subjects. Can easily be searched.
Breaking News English - Current events and general interest stories recorded in American or British accents which can be played at different speeds. Many online exercises with each story. Includes listening, reading, grammar, spelling and vocabulary activities.