A few sites you may find worth bookmarking, or at least visiting.
Strunk & White is the base style guide for many newspapers and press galleries. If you want to look up a grammar or usage question, this is the place to go.
The alt.usage.english newsgroup. If you'd like every sentence chewed over, dissected, and then rewritten several conflicting ways, or some great advice about bacon, you'll find both here. Many real live editors and authors hang out here, and they do know their stuff. Just make sure you read all ten or so FAQ's before asking a question.