AllExperts has volunteers ready to answer questions on more than 1500 topics.
Ask Dr. Math
Ask Dr. Math is a question and answer service for math students and their teachers. A searchable archive is available by level and topic, as well as summaries of Frequently Asked Questions.
Ask a Scientist
A great resource for students and teachers from SCORE (Schools of California On-line Resources for Education). Other parts of the site include Kid's Place, Teacher's Place, Science Search and Science Networks.
Ask the Experts
Search the archives of this extensive list of science and health related questions and answers from Scientific American
Homework Center: Science
Provided by the publishers of Information Please.
King County (WA) Library
Hundreds of annotated links for all subjects sorted by subject area and annotated.
Mad Scientist Network
In addition to archives of more than 36,000 questions and answers, find a library of web sites, and a set ot edible / inedible experiments.
National Geographic Homework Help
Pictures, articles, maps for use in student reports, presentations, and more.