Guitar Definitions - from guitar secrets.com includes lessons as well
Music Theory - from Ricci Adam's Music Theory.net Not only does the online music site provide lessons in everything from basic intervals to Neapolitan chords, there are also a large number of exercises. Additional utilities include a chord calculator and a matrix calculator for serialism lessons. Additionally, there are basic exercises in aural theory and chords. The online lesson have simple explanations and are accompanied by audio examples.
Music Theory - This music site provides online lessons from everything from chords and rhythms to figured bass. Simple diagrams and easy explanations can help music students in basic theory and students wanting to refresh their skills.
emusic theory - This theory website provides a number of drills in chords and intervals, as well as other basic music theory skills. Although there are some problems with loading time and the interface may be a little confusing the first time, the drills here are an invaluable resource for basic music theory students and teachers.
Free Music Theory Lessons for Advanced Guitar Players - This online website is great for students who have learned how to play their instrument by ear but do not know how to read music. The lessons are broken down into the simplest terms, also appropriate for elementary school age. A variety of topics are presented, from 7th chords and major scales to guitar specific lessons on the guitar fingerboard.
Theory on the Web - Theory on the Web provides lesson plans with audio examples online for students and teachers. The lessons are a little more in depth than some of the other online resources, covering topics from rhythm to the overtone series to harmonization. Theory on the Web also provides blank music sheet paper for free for teachers and students to print through Adobe Reader.
Music Research - This web site, from the University of Miami, is designed to assist researchers in conducting music research. Numerous links are available to assist in doing library research, collecting data, analyzing the data, writing the research report, and disseminating the research.
Center for Computer Research in Music and Acoustics - The Stanford Center for Computer Research in Music and Acoustics (CCRMA) is a multi-disciplinary facility where composers and researchers work together using computer-based technology both as an artistic medium and as a research tool.
Music Research - This web site is designed to assist researchers in conducting music research. Numerous links are available to assist in doing library research, collecting data, analyzing the data, writing the research report, and disseminating the research.