University of Michigan
U.michigan: Keyboard Temperament Analyzer
Features a downloadable spreadsheet for analyzing keyboard temperaments. Requires a bit of physics knowledge.
Music Theory
Music theory.net: Keyboard Trainer
A fantastic resource for music teachers and students learning to play the piano. This online quiz can be customized to test students on specific keys. Students can click "Toggle helpers," to check answers along the way.
Other
Tb on Web: Alternate Temperaments Theory and Philosophy
Explanation of various keyboard tunings, and why modern Western music uses "equal temperament."
Yale University
Yale Collection of Musical Instruments: Keyboard Instruments
Learn about keyboard instruments from the collection of Yale University in this image gallery with descriptions of each piece, including pianos, harpsichords, and organs.
Other
Online Mallet Lessons
This site contains numerous tips and suggestions dealing with many facets of playing the vibraphone and marimba. Although much of the information is jazz oriented, some is general enough that it could easily be applied to xylophone and...
Other
Vic Firth: Educator's Resource Library
This website is a cornucopia of resources for percussion instruction. There are videos, audiocasts, podcasts, interviews with talented percussionists. Please check out this website is you are interested in any aspect of percussion.
Indiana University
History and Literature of Music: Renaissance Instruments
This resource classifies Renaissance instruments in the following categories: winds, plucked strings, bowed strings, keyboard, and percussion.
Other
The Abc's of Chord Voicings
The concept of chord voicings for keyboard instruments is illustrated by this site. Material could also relate to pianists who would like to learn voicing. MIDI files are included for added demonstration
Other
What Are Historical Keyboard Instruments
Provides information about historical keyboard instruments such as the clavichord, harpsichord, fortepiano and organ.
Dallas Symphony Orchestra
Dallas Symphony Orchestra Kids: Piano
Read about keyboard instruments and the piano in particular. Use RealAudio or Windows Media Player to hear the piano alone and with the orchestra.
Dallas Symphony Orchestra
Dallas Symphony Orchestra Kids: Organ
A concert hall organ can have as many as four keyboards, 244 keys, 32 pedals and 4,535 pipes. Use RealAudio or Windows Media Player to hear the organ alone or with the orchestra.
Other
Piano Music Sight Reading Practice
Actually this clever site drills pianists on note names and note placement on the keyboard. Kids can access this site at home for practice. Both treble and bass clef are used.