Teacher Pearson Brown specializes in teaching business English and offers several useful resources in his websites. At Better-English you will find exercises on grammar, vocabulary and
idioms - all focusing on business language. On the left menu it is possible to access additional quizzes, including phrasal verbs. Recommended for intermediate students.

ESL Blues has a nice collection of online exercises for students with pre-intermediate or intermediate English. There“s grammar, reading and vocabulary including problem words and common mistakes. Also nice are the animated grammar tutorials, which cover basic verb tenses such as Past and Present Simple.
This is an amazing collection of English exercises - here you’ll find exercises in
regular English, literature-based, with texts, with games, drag-and-drop, theme-based, bilingual, for health professionals (for job-related exercises, take a look at Special Purposes), with audio and much more. The exercises aren’t separated by level - you have to check out different topics to see what’s available, but this huge collection is greatly recommended for students looking for practice with their English skills.
To make it easier for students, About’s English section has all the quizzes organized in one easy index. All exercises can be done online and always include the answer key. You’ll find everything: grammar (including reviews for the TOEFL exam), slang, phrasal verbs, idioms, vocabulary and audio exercises. It’s a whole lot in one place - really worth taking a look.
English Forum is a portal that gathers exercises from many different websites in
one place (click on Interactive Exercises) - there’s grammar, vocabulary, games and other activities. You’ll also find a worldwide English school directory, and for students having trouble with English grammar, ask your questions in the Students Message Board. Teachers may want to take a look at this directory of schools and ESL news.
BBC offers Skillswise, a mini portal with several well organized activities for English learners. One of the highlights is the Grammar section, which currently has 11 lessons with factsheet, game, quiz and exercise worksheet. A few topics: adverbs, personal pronouns and adjectives.
Also very nice is the Spelling section, which talks about Letter Patterns such as sight, bright, light, etc. If you visit Skillswise, make sure you take a look at all the sections - the whole site has a pleasant feel and the content is good without being excessive.