Bad Astronomy (site showcasing bad and erroneous science)
www.badastronomy.com/

Bagheera's Endangered Species Page
www.bagheera.com

Becoming Human (broadband documentary on human evolution)
www.becominghuman.org/

Beneficial Insects (in with the good bugs, out with the bad...)
www.ext.vt.edu/departments/entomology/ornamentals/beneficials.html

Bureau of Atomic Tourism (want to visit some nuclear test sites?)
www.atomictourist.com/

Carolina Coastal Science
www.ncsu.edu/coast/index.html

Cool Science for Curious Kids
www.hhmi.org/coolscience/

Dinorama (if you or your kids are into the big beasties, surf here)
www.nationalgeographic.com/dinorama/

Earthamaps (see a map of any city or location via the place, Zip code, area code, or latitude/longitude)
www.earthamaps.com/

Earthpulse (National Geographic interactive site full of multimedia presentations about the wonders of the planet)
www.nationalgeographic.com/earthpulse/

eNature (a National Wildlife Federation-acquired site that maintains a compendium of info on wildlife, habitats, and outdoor activities)
www.enature.com/

Fahrenheit to Celsius Converter (and vice versa)
www.wbuf.noaa.gov/tempfc.htm

Foliage Network (updated info on the changing seasons and Nature's related displays of foliage and color)
www.foliagenetwork.com/

Froguts (virtual frog dissection)
www.froguts.com/

The Heart - An Online Exploration (good site for info about the human heart)
sln.fi.edu/biosci/heart.html

Heavens-Above (excellent site for tracking satellites and other astronomical info)
www.heavens-above.com/main.asp

Herman the Worm (great site for learning about earthworms and the ways they interact with our environment)
www.urbanext.uiuc.edu/worms/index.html

HubbleSite (lots of graphical presentations and info about the Hubble Space Telescope -- some beautiful stuff here)
hubble.stsci.edu/

Infection Detection (kids' site; fun facts about microbes, etc.)
www.amnh.org/nationalcenter/infection/index.html

Inner Body (good educational site for the body's inner workings)
www.innerbody.com/htm/body.html

Insects on the Web (great site for kids and adults who are interested in the wide, wide world of bugs)
www.bugbios.com/

Interactive Star Chart (wonder what constellations are overhead right now? find out here)
www.mystarslive.com/

International Space University (renowned online graduate school granting diplomas in various aerospace and science fields)
www.isunet.edu/

JASON Project (online home of the famous Jason oceanographic exploration)
www.jasonproject.org/

JunkScience (a site devoted to debunking the fraudulent and mythical aspects of popular scientific beliefs; be warned, they seem to have a political agenda also)
www.junkscience.com/

Jurassic Park Institute (all things dino)
www.jpinstitute.com/

Keith's Astronomy and Astrophotography Page
home.HiWAAY.net/~krcool/Astro/Astro2.htm

Microsoft Terraserver (a huge compendium of satellite images of Earth from U.S. and Russian sources -- hey, I can see my house from here!)
terraserver.microsoft.com/

Minax Tarantulas (site devoted to the 843 species of tarantulas)
hem.spray.se/minax/index/welcome_e.html

NASA Human Space Flight (keep up with current missions, spaceflight-sighting opportunities, and more)
www.spaceflight.nasa.gov/

National Geographic Society (plenty of interactive features, maps, and what have you)
www.nationalgeographic.com/

National Oceanic and Atmospheric Administration: OSEI (cool weather satellite images)
www.osei.noaa.gov/

Natural History Museum: Dino Directory (excellent dinosaur resource)
flood.nhm.ac.uk/cgi-bin/dino/

Nature Conservancy (venerable naturalist and environmental organization)
www.nature.org/

Neuroscience for Kids (explore a virtual central nervous system)
faculty.washington.edu/chudler/introb.html

New Scientist (online presence of the respected science magazine)
www.newscientist.com/

Nine Planets (multimedia tour of the Solar System)
seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html

Nuclear Blast Mapper (choose where you want to bomb and how big you want to make your blast, and watch the fun begin...virtually, of course)
www.pbs.org/wgbh/pages/amex/bomb/sfeature/mapablast.html

Ocean Planet (Smithsonian site with lots of info, pictorials, lesson plans, more)
http://seawifs.gsfc.nasa.gov/ocean_planet.html

Old Farmer's Almanac (folksy rendition of the old standby -- weather, planting information, and lots of tidbits)
www.almanac.com/

Ology (comprehensive informational site from the American Museum of Natural History)
www.ology.amnh.org/

Popular Science (online presence of the venerable tech mag)
www.popsci.com/

Science Education Gateway (collaborative site using talents of NASA scientists and K-12 educators to produce curricula and resources)
cse.ssl.berkeley.edu/segway/index.html

Smart Planet (good site for computer learning and certification)
www.zdnet.com/smartplanet/

Solar System Lesson Plans
www.lalc.k12.ca.us/laep/smart/Sunrise/sunhome.html

Sport! Science (the science behind the sports)
www.exploratorium.edu/sports/index.html

Station Location (find out where the larger of the gazillion man-made objects in Earth orbit are, their orbital paths, etc.)
liftoff.msfc.nasa.gov/temp/StationLoc.html

Sun Protection (all kinds of info about the sun's effect on our health)
www.sunprotection.org/

Terrafly (take a virtual flying tour of any locale on the globe)
terrafly.fiu.edu/

Union of Concerned Scientists (large site with an alarming amount of info about the width and variety of destructive influences on our environment)
www.ucsusa.org/index.html

Vegetable Insects (an exhaustive listing)
entweb.clemson.edu/cuentres/cesheets/veg/

Visual Elements Periodic Table (elegant, interactive site bringing the dry old Periodic Table to life)
www.chemsoc.org/viselements/pages/periodic_table.html

Visual Physics (oddly designed simulation site)
library.thinkquest.org/10170/main.htm

Volcano World (track the world's volcanic activity here)
volcano.und.nodak.edu/vw.html

Weather Underground (not the site for the '60s anarchist organization, but a comprehensive site dealing with weather all over the globe)
www.wunderground.com/

The Why? Files (source of info for the science behind the current headlines)
whyfiles.org/

World Magazine (monthly online 'zine for kids, from National Geographic)
www.nationalgeographic.com/world/index.html

More to come...