i personally recommend the following website:
http://www.jgram.org/
the explanations are in English, but there are example sentences in Japanese, with English translations that follow, which show how to use the grammar point correctly. i find that when i am studying Japanese grammar, even though I can understand most of the Japanese explanations that are written, I often like to check up on my understanding by referring to the corresponding English translations.
i also enjoy using the "grammar by email" service, which sends you one Japanese grammar point a day to your email address. this is a good way to review/learn some Japanese while you concentrate on other areas (such as reading and listening).