Burt and Company Music - most comprehensive and reliable source for sheet music and metronomes (I recommend the SQ50) Fast delivery with UPS or USPS from Marlton, NJ.
www.sheetmusic.com - Easy to use search engine. Ships from California.
Music Teachers National Association
Suzuki Association of the Americas - subscribe to the journal; great parent survival articles and summer music camp listings.
ArkivMusic - Classical music compact discs.
Music Theory.Net- FREE, interactive website for students who wish to learn music theory on their own or for the student that needs extra drill with chords, intervals note names, etc. Both visual and aural exercises. Covers a host of theory topics from elementary level up to secondary dominants, neapolitan and augmented sixth chords.
www.allpianoscores.com - FREE piano score downloads. Organized alphabetically by composer
International Music Score Library Project - FREE, virtual library containing all public domain musical scores. Great source for chamber music (full scores and individual parts)