A Writing Kit - The University of Ottawa's Academic Writing Help Centre (AWHC) has an online "writing kit," with "6 steps to writing" some basic grammar tips, style guides for MLA, APA and the Chicago Manual and a "comparison table "that looks at all three styles side by side.
Purdue's Writing Lab (OWL) - The LAC staff consider Purdue's "virtual writing lab" to be the best site devoted to writing on the web. The site is user friendly and includes information on style, argument, research, drafting, and grammar. The handouts are clear and available in both PDF and printer friendly format.
Chuck Guilford's Paradigm Online Writing Assistant - A well designed, clean site with exercises for brainstorming, organizing your writing, revising your writing, as well as information on writing informal, thesis/support, argumentative, and exploratory essays.
The Writing Center - The University of North Carolina at Chapel Hill has an excellent writing site with an extensive series of clear and in-depth handouts covering topics ranging from fragments and run-ons to dissertations. In addition to the handouts, there is also a series of annotated links to other writing sites. Be warned; they are a bit harder to find than the handouts.
Duke University Libraries - This link to Duke Library provides useful information including choosing a topic, finding general information, refining a topic, selecting and evaluating resources, and citing sources. The information is presented from a research perspective rather than a paper writing perspective.
Writing Help for History Students - This site, by Professor Greg Smith of the University of Manitoba History Department, offers links to online resources that will help students write history assignments, and includes information on proper format methods and writing styles for specific writing assignments such as critical book reviews, document studies, and research essays.