Once upon a time I had a large collection of useful websites to assist learners of English. I guess it is time I dusted off that collection. I also have a huge collection of books although not all will be available. I'll try to figure out which I think are the cream of the crop.
First share is: http://grammarbook.com This site was originally a free resource to help people improve their English and it is still free although they now publish "The Blue Book of Grammar" also.