The following is a collection of links to web pages on science fair projects. 
Hopefully these sites will be informative. 
Please use them with your child at your own discretion.

The World Wide Web’s Virtual Library: Science Fairs
http://physics.usc.edu/~gould/ScienceFairs/
This Library page is an attempt to provide a single comprehensive list of every science fair accessible through the World Wide Web, whether of global or local scope. Here's how to make corrections or add new science fairs to the list. This document is part of the World-Wide Web Virtual Library. Information categorized by subject.

Science Fair Project on the Web
http://sciencefairproject.virtualave.net/
This one is all inclusive. It will help elementary to high school. This includes steps of a science fair project, The scientific method, judging sheet examples, and teacher resources!

Kidspace@The Internet Public Library
http://ipl.si.umich.edu/div/kidspace/projectguide/
The IPL will guide you to a variety of web site resources, leading you through the necessary steps to successfully complete a science experiment.

School Discovery.com’s Science Fair Central
http://school.discovery.com/sciencefaircentral/
A comprehensive guide to creating your science fair project!

SciFair.org Presents: The Ultimate Science Fair Resource
http://www.scifair.org/
Welcome to The Ultimate Science Fair Resource, the Internet's premiere resource for science fair. Whether you are a student trying to find an idea for a project, a parent or teacher looking for information on building displays, or for the delight of experimentation you'll find it here.

Cyber-Fair: A Resource for Elementary Science Students
http://www.isd77.k12.mn.us/resources/cf/steps.html
This site will take you through the steps to prepare a science fair project.

Science Fairs Homepage
http://www.stemnet.nf.ca/sciencefairs/
This is a  project of the Eastern Newfoundland Science Fairs Council, this homepage is designed to aid students in the most difficult aspect of their science fair experience; getting an idea. They have everything from coolinks to information on the  Canada Wide Science Fair. They have also included the listing of many science project ideas and hope to include more in the future.

http://www.sciencebuddies.org
This site provides ideas for science fair projects based on individual interests by student's responses to a questionnaire about their likes and dislikes.

http://scifair.org
This site includes project steps and hints, report writing aid, display boards, and idea bank. For children, parents, and teachers

http://www.all-science-fair-projects.com/
Over 500 Free Science Fair Projects with Complete Instructions.

http://www.cyberbee.com/science/prep.html
Discover the wonderful world of science with these tips and materials from the professionals.

http://faculty.washington.edu/chudler/fair.html
This site presents the steps involved in creating a science fair project in a clear and easy-to-read manner. It was created with students in mind as the audience. The author is a science teacher, former science fair organizer and judge.

http://web.mit.edu/invent/r-archive-2.html
MIT's Invention Dimension:  Fun Sites for Kids

http://www.exploratorium.edu/explore/handson.html
Exploratorium's Hands-on Activities

Other Science Fair Sites:

   COOL SCIENCE JUNK, mail order catalogs!

   Science Fair Help (madsci site)

   Build a VOLCANO

   Yahoo - Science Fair Guides

   Science Fair Home Page

   School Science Fair Websites (huge index)

   Science Project Introduction

http://www.freesciencefairproject.com/primary_projects.htm

http://www.twingroves.district96.k12.il.us/ScienceInternet/BehavioralTopics.html

http://faculty.washington.edu/chudler/experi.html

www.sciencebuddies.com

http://earthquake.usgs.gov/4kids/sciencefair.html

http://www.lasciencefair.org/ideas.htm

http://othello.mech.northwestern.edu/~peshkin/scifair/chias_ideas.html

http://www.cyberbee.com/science/sciproj.html

http://www.sciencemadesimple.com/projects.html