MissEnglish.com

Blue Book of Grammar and punctuation
Grammar and punctuation reference guide including exercises with answers.
www.grammarbook.com/

Grammar and Punctuation in American English
A site that contains information on grammar and punctuation, including parts of speech and parts of sentences.
www.geocities.com/

The Internet Grammar of English
Course written primarily for university undergraduates but useful for anyone as it doesn't presume any prior knowledge of grammar. Free for students who log in from a UK university and all explanations are free.
www.ucl.ac.uk/

English Grammar Online
Offers exercises, explanations (grammar, writing), games, literature, teaching materials and information on English-speaking countries
www.ego4u.com/

Tutoring English Grammar and Composition
Scripted exercises for tutoring basic English grammar and composition.
www.sfo.com/

English for Techies
By Christian Lassure, associate professor of English. For French student technologists. Grammar, false friends, translation methods, glossaries. Mechanical production engineering, industrial computing, and computer graphics.
www.english-for-techies.net/

English Grammar
Describes the different parts of a sentence and provides examples of correct and incorrect usage.
www.iscribe.org/

Professor Grammar
Includes games and a video grammar lesson. Requires RealAudio.
www.professorgrammar.com/

Learn English Today
Free grammar and vocabulary section, idioms, exercises and links to news articles and recommended books.
www.learn-english-today.com/

Indiana State University Grammar
Includes information on irregular verbs, modals, plurals, prepositions, tense and aspect, two-word verbs, and article usage.
isu.indstate.edu/