Science

Ask A Geologist
Do you have a question about volcanoes, earthquakes, mountains, rocks, maps, ground water, lakes, or rivers? A service of the earth scientists at USGS.
http://walrus.wr.usgs.gov/ask-a-geologist/

Ask a Marine Science Expert
Email your question after checking the archive of previous questions and answers.
http://whale.wheelock.edu/whalenet-stuff/ASK_SCI.html

Ask a Rocket Scientist
Explains design, technology, aerodynamics, history, space travel, and other topics related to aerospace engineering.
http://www.aerospaceweb.org/question/

Ask A Scientist
You can ask a scientist a question on the WWW MadSciNet: The 24-hour exploding laboratory.
http://www.madsci.org/submit.html

Ask An Aviculture Expert
Birds and bird care questions. Not a substitute for a trip to the vet.
http://www.upatsix.com/ask-experts/

Ask an Earth Scientist
Experts at the U of Hawaii answer questions about volcanoes and igneous rocks, earthquakes and seismology, natural disasters, geochemistry, the environment, pollution, hydrology and water quality, minerals, gems and crystals, geophysics, sediments and sedimentary rocks, and just plain ol' geology.
http://www.soest.hawaii.edu/GG/ASK/askanerd.html

Ask Dr. Universe
Dr. Universe has a whole university full of experts ready to tackle your question on any subject. Explore the question of the day, and longer featured answers.
http://www.wsu.edu/DrUniverse/

Ask Mr. Water Wizard
Do you have questions about water? Questions about water quality in some nearby stream or lake? About drinking water? About water quality testing? About aquatic life such as fish, turtles, snakes, and insects, in your local waterways? Mr. Water Wizard can help.
http://www.sra.dst.tx.us/srwmp/mr_water_wizard/default.asp

Ask Shamu
Ask and read archives of questions and answers. Mainly about marine biology and the environment.
http://www.seaworld.org/ask-shamu/faq.htm

Ask The Space Scientist
Ask a question and check out the archives for the many questions asked at this site.
http://image.gsfc.nasa.gov/poetry/ask/askmag.html

Curious about Astronomy? Ask an Astronomer!
Browse archives of previous questions and answers, or submit a question to be answered by astronomers at Cornell University.
http://curious.astro.cornell.edu/

How Things Work
Ask about almost anything related to the physical world, and check the well-organized archives for answers to previous interesting questions.
http://howthingswork.virginia.edu/

NEWTON Bulletin Board System
Ask-a-scientist service designed for K-12 teachers and their students - operated by the Argonne Nat'l. Laboratory, Div. of Educational Programs.
http://www.newton.dep.anl.gov/

Physlink - Ask Experts Physics and Astronomy Questions
Ask questions and check out the archives, organized by topic.
http://www.physlink.com/Education/AskExperts/Index.cfm

Science Questions & Answers
Expert responses to questions on biology, chemistry, geology, and other branches of science.
http://www.sciam.com/askexpert_directory.cfm

What is? What!
Aims to give you easy answers to everyday questions. We define words, acronyms, and ideas. We have a computer-related and open-source slant.
http://what-is-what.com

WonderQuest with April Holladay
Check out the archives at WonderQuest, or ask a question for answers to conundrums about the world around us.
http://www.wonderquest.com