The Writing Den is a good little reference website for student writers. The Writing Den offers students a word of the day, tips on grammar rules, and tips on sentence and paragraph construction. For teachers the Writing Den offers seven ideas for using the resources on Writing Den in their classrooms.
Applications for Education
The Writing Den has a definite web 1.0 feel, yet still offers some good tips that can be used by students and teachers.
Here are some related resources that may be of interest to you:
Essay Map – Step-by-Step Help Constructing Essays
Grammar Bytes – Develop and Test Grammar Knowledge
Language Arts Links You Might Have Missed