This website, updated on an almost daily basis, gives you the option to listen to a podcast of the day's tips or read the transcript. You can also subscribe to Grammar Girl's free newsletter and read her Top Five Tips.
This website was created by Mignon Fogarty, a former magazine and technical writer.
Guide to Grammar and Writing is an interactive site where you choose specific grammar lessons that you want to work on.
Old enough to remember "Schoolhouse Rocks"? This site is a compilation of the old schoolhouse rocks musical rhymes to remember grammar rules. Who says grammar can't be fun?!
The Center for Writing Studies at the University of Illinois has an online Grammar Handbook. Included are
- Parts of speech
- Sentence elments
- Common usage problems
The Writing Resource Center at Empire State College has details on a number of common grammatical subjects. It includes exercises so you can practice what you learn
Grammar Monster has lots of lessons on specific grammar topics. There are also quizzes so that you can test yourself and see if you have understood the lesson.