This page has links to sites that you can use as a reference for all those questions that come up in your job. Some are also student-friendly.

Rikai is a site designed to help your students read English webpages. It shows the Japanese translation for any word you move the mouse over.
http://www.rikai.com

Quizzes offers hundreds and hundreds of quizzes to test you and your students at any level.
http://a4esl.org

Your Dictionary has 290 dictionaries including rhyming dictionaries, links to grammar courses of different languages and glossaries.
http://www.yourdictionary.com

Ask Oxford has answers to any question about English, as well as games.
http://www.askoxford.com

Classic Reader is a collection of 771 out-of-copyright books and 1041 classic short stories.
http://www.classicreader.com

Project Gutenberg another resource of 6276 out-of-copyright books downloadable for use in class.
http://promo.net/pg

An anonymous siteowner offers a bank of classic short stories.
http://mbhs.bergtraum.k12.ny.us/cybereng/shorts/

Sheffield Hallam University TESOL department has a bank of information on meanings - origins of sayings, cliches and quotes.
http://phrases.shu.ac.uk/meanings

Kaiteki net is a Japanese site that offers advise on listening to English on the Web.
http://www.kaiteki-net.com/online_english/index.html

Teen Space is a part of the Inetrnet Public Library run by the University of Michigan School of Information and is a guide to researching and writing.
http://www.ipl.si.umich.edu/div/teen/aplus/

Bartleby is an authoritative guide to contemporary English.
http://www.bartelby.com/64/