See also, Technical Writing Guides.

Links to online help:

How to Make a Great Poster
By Dina F. Mandoli, University of Washington, some ideas about how to get the most attention for your efforts.

How to Have Your Abstract Rejected
By Mary-Claire van Leunen and Richard Lipton, strategies for making your abstract suitable for rejection.

Links to published help:

Scientist's Guide to Poster Presentations
by Peter J. Gosling

Scientific Papers and Presentations
by Martha Davis

Preparing Scientific Illustrations: A Guide to Better Posters, Presentations, and Publications
by Mary Helen Briscoe

Communicating in Science : Writing a Scientific Paper and Speaking at Scientific Meetings
by Vernon Booth

The Craft of Scientific Presentations: Critical Steps to Succeed and Critical Errors to Avoid
by Michael Alley

How to produce an awful PowerPoint presentation min-eng.blogspot.com/2010/01/how-to-produce-awful-powerpoint.html

How to deliver an awful oral presentation min-eng.blogspot.com/2010/01/how-to-deliver-awful-oral-presentation.html