ESL BLues. Grammar. Grammar notes. Vocabulary. Reading

Skillswise games. Grammar. Spelling. Reading. Listening. Vocabulary.

English at Home: A well organized site. It even has a "Help Me" forum.

BBC: English language experts answer common language problems sent in by learners.

Interesting Things for Students: Grammar, vocabulary, but also lots of listening practice.

Grammar

English Grammar Quizzes.

Netgrammar : Explanations, exercises and skills practice.

Grammarman Comics to practise grammar

Road to Grammar. Interactive quizzes and puzzles

Class Zone. Grammar games

British Council. Grammar games

The Virtual Grammar Lab. Lots of activities

Movie Segments To Assess Grammar Goals