Writing is a craft which can be practiced and refined, and for which each individual follows a very personal path.
For that reason the list of links may be relevant and useful to all sorts of different people, at all sorts of levels, for all sorts of purposes.
Introductory - and foundational
Purdue Online Writing Lab
Helpful source of guidance, which covers the whole gamut on academic writing.
Here is a link to writing annotated bibliographies from Purdue. The sub task of creating an annotated bibliography is a key component of the skill used in academic writing - particularly relevant to the related works/literature review section of formal papers http://owl.english.purdue.edu/owl/resource/614/01/
More Advanced Level
Tomorrow's Professor is a website run out of Stanford which is a frequent helpful source of information and advice
Tomorrow's Professor Msg.#1107 Writing an Article in 12 Weeks
IN HER BOOK WRITING YOUR JOURNAL ARTICLE in 12 Weeks: A Guide to Academic Publishing Success, Wendy Laura Belcher breaks down the writing process into manageable tasks to help anyone prepare an article for publication in just 12 weeks.
... gives some great tips on the use of present and past tenses in your writing. It is from the February 2010 issue of the online publication Graduate Connections Newsletter [http://www.unl.edu/gradstudies/current/dev/newsletter/] , pp 16-17, from the University of Nebraska-Lincoln and is published by the Office of Graduate Studies. ©2010 Graduate Studies, University of Nebraska-Lincoln. Reprinted with permission.
...a short piece on the development of a new book, Demystifying Dissertation Writing: A Streamlined Process from Choice of Topic to Final text, by Peg Boyle Single, Ph.D. Published by Stylus Publishing, LLC 22883 Quicksilver Drive, Sterling, Virginia, 20166-2102. ©2010 Peg Boyle Single.