John Jay's Writing Center - schedule of writing center workshops, hours, and some helpful instructional material under Resources, in addition to links to other online writing laboratories
City College Writing Center - has many helpful online handouts which provide aid at every stage of the writing process: from organizing a paper, to doing an outline, to defining your thesis statement, to integrating sources, and paraphrasing.
CUNY WriteSite - offers help with grammar and style, the writing process, and hints for how to handle various kinds of writing, throughout the disciplines. Interactive practice exercises available.
Purdue University Online Writing Laboratory (OWL) - offers a wealth of information about writing including handouts. workshops, and other Internet writing sites. Try browsing their list of handouts!
Writer's Handbook - from the University of Wisconsin, Madison Writing Center - a comprehensive writing resource with sections on:
Stages of the writing process - getting started, drafting, revising, proofreading, etc.