Guide to Grammar and Writing: A high-quality selection of English grammar quizzes.
Maintained by Professor Charles Darling at Capital Community College.
NetGrammar: Provides extensive grammar practice through a great variety of reading, writing and listening activities.
Suitable for self-directed learning and also as an extension to regular classwork.
StudyEnglishToday.net: Offers free online English lessons and English grammar for ESL and EFL learners. Includes also tests, English alphabet with pictures of animals, poetry and lyrics.
The Internet Grammar of English: Complete online grammar with interactive exercises.
Online course in English grammar, written in 1996-1998 and designed at the Survey of English Usage, a research unit based at University College London.