Writing Resources on the Web--Sweetland Writing Center
Many helpful resources, from brainstorming through revision.  Check out Sweetland's one-on-one writing workshops and  OWL (On-line Writing and Learning Lab). 

OWL: Writing A Research Paper Workshop--Purdue University 
Step-by-step guide the process of writing a research paper.

Proofreading

Strunk and White, Essentials of Writing

APA Style Guide

MLA Style Guide

Interactive Assignment Calculator.  Three weeks before that paper is due?  Or only three days?  This helpful interactive site from the University of Minnesota helps you plan how to make the best use of the time you have to do an assignment as thoroughly as you can. (Remember to link to the UM library system, though!)