For fun review of what you learned in high school:
1. GrammarGirl is a pretty reliable site for all things grammar.
2. Grammarly.com/handbook has good resources.
3. UsingEnglish.com has some terrific lists of . . . .
4. EnglishGrammarSecrets.com also has a good list of exercises.
For a good list of grammar activities, see these:
2. EnglishGrammar101.com will take you from simple verb identification to discerning differences in the meanings of words.
3. About.com has a good list of grammar terms.
And a list of
4. rhetorical terms.