Enjoy this collection of links on a wide variety of helpful topics! Immediately following those are several projects.

ASTRONOMY

About Space & Astronomy for Kids
Amazing Space
Astronomy
Astronomy for Kids
Basics of Space Flight Workbook
Athena Earth & Space Science for K-12
Exploring Planets in the Classroom
Exploring the Moon
How Things Fly
How to Start Right in Astronomy
Kitt Peak National Observatory
Making a Coment In the Classroom
Mars' Happy Face: Have a Nice Planet!
Mir Space Station
NASA
Project Galileo: Bringing Jupiter to Earth
Skywatching Center
Solar Energy Science Projects
Solar System Live
Solar System Simulator
Space and Astronomy
Space and Astronomy for Kids
Space and Its Exploration
StarChild
Star Journey at National Geographic
StarLight StarBright
The Universe
Virtual Solar System
Windows to the Universe

EARTH SCIENCE

An Herbarium
4-H Dairy Publications
Fresh California Grapes Classroom & Playground
Kids in the Garden
NASA's Earth Observatory
Plants
Nutrition Expedition: Trails to Explore
Rock Classification
Tornadoes: Lesson Plan

ANIMALS

Animals
Animals From A to Z
Caterpillars and Butterflies
Class: Insecta
Cyber Tiger: You're the Zookeeper
Euro Turtle
Frogs
Journey North: A Global Study of Wildlife Migration
The Great Dinosaur Mystery
Y.E.S. Minibeast World

HUMANS

A Sensory Summer
BodyQuest
A Guided Tour of the Virtual Human
Human Anatomy Online
Neuroscience for Kids

CHEMISTRY

Bizarre Stuff You Can Make In Your Kitchen
Chemistry
Chemistry Teaching Resources
ChemTeam: A Tutorial for High School Chemistry
Crystal Growing Recipes
General Chemistry Online
Molecular Models
Ooey Gooey Recipes for the Classroom
The Periodic Table
Rader's Chem4Kids
Recipes for Growing Sugar Crystals

MARINE STUDIES

Neptune's Web
Ocean of Know
SeaWiFS Project
Something's Fishy
Oceans All Over
Theme: Oceans and Undersea Life
Treasures@sea: Exploring the Ocean Through Literature
WaterWorks

AND MORE!

Alexander Graham Bell's Path to the Telephone
Automotive Learning Online
Bill Nye the Science Guy's NYE LABS ONLINE
Constructor
The Cyberspace Middle School
Electric Universe
From the Ground Up
How Things Work
K-12 Science Lesson Plans
Lawrence Hall of Science
1998 HHMI Holiday Lectures On Science
Home School Adventures -- Science Camp at Home: Mouse Meadows
Magnets
The Nutty Hatch
Picture It
Reeko's Mad Scientist Lab
Science Fairs Homepage
Science in the Elementary School
Science Learning Network
Science Made Simple
Science Worksheets
Science Junction Teacher Terminal
Thinking Fountain
Visualize Science
The Yuckiest Site on the Internet

Check back soon for some helpful lesson tips I've picked up from wandering the internet! I had some up, but my server inadvertently deleted them.