Music Theory Online (http://www.dolmetsch.com/introduction.htm)

       LOTS of theory explanation along with history, instruments, and more
Music Theory (http://library.thinkquest.org/15413/theory/theory.htm)

       Good simple explanations of basic fundamentals and music theory
eMusicTheory.com (http://www.emusictheory.com/practice.html)

       GREAT online exercises to practice with!
MiBAC (http://www.mibac.com/Pages/Theory/Main_Theory.htm)

       Stands for Music Instruction By A Computer. Lots of basics.
Teoria.com (http://www.teoria.com/)

       In Spanish and English. Exercises, references, and tutorials.

Essentials of Music (http://www.essentialsofmusic.com/)

       Music History, Composer info (with audio clips), and GLOSSARY of musical terms

Today In Music History (http://www.musicorb.com/index.php)

       See events, birthdays, and other things that happened in different kinds of music
A History of Western Music (http://www.wwnorton.com/grout/index.htm)

       Outlines and quizzes from one of the most common music history texts.
Dr. Estrella's Incredibly Abridged Dictionary of Composers

    (http://www.stevenestrella.com/composers/index.html)

       A list of composers, timelines, and other great information.
ClassicalNet (http://www.classical.net/music/)

       Composer biographies, brief historical era descriptions and much more
Classical Composer Database

   (http://www.classical-composers.org/cgi-bin/ccd.cgi?comp=_phome)

      Search 2740 composers for info, pictures, works, etc.

Classical Composer Archive (http://voyager.physics.unlv.edu/webpages2/picgalr2.html)

      Composers arranged by the country of origin.

Violin Masterclass (http://violinmasterclass.com/home.php)

       Great site with videos on string technique!

ViolinSpot.com (http://www.violinspot.com/index.html)

       Neat site with things like downloadable staff paper, music, and more.
Internet Cello Society (http://www.cello.org/)

       All things cello -- mp3s, associations, stores, and much more.
Everything Cello (http://www.everythingcello.com/)

       The name of the site says it all - a store for all you need.
The Viola Web Site (http://www.viola.com/)

       A site with lots of resources for the viola player.
American Viola Society (http://www.americanviolasociety.org/)

      The "academic" side of the viola world.