• American Choral Directors' Association (ACDA)
• Chorister's Guild
• National Association of Pastoral Musicians (NAPM)

Handbells

• American Guild of English Handbell Ringers (AGEHR)
• Ringem.org, the server for a mailing list called Handbell-L
• Gold Coast Music
• Sound Innovation
• Genesis Press, level 1&2 handbell music
• Cantabile Press, small ensemble handbell music

Organ

• American Guild of Organists (AGO)
• MPR's Pipedreams
• Organ clearing house (information on obtaining pipe organs from defunct churches)

Music planning & references

• Music planning calendar from the National Association of Pastoral Musicians
• Anglican Online Hymnal
• MUSICA, a choral music database
• ASCAP
• Christian Copyright Licensing International (CCLI)
• GIA Publications

Free sheet music

• Choral Public Domain Library
• Mutopia project
• Werner Icking Music Archive
• Project Gutenburg music files
• mfiles
• a collection of songbooks in PDF format
• HymnWiki
• Wikifonia, a source for miscellaneous lead sheets
• the Lester S. Levy collection of sheet music
• Free Sheetmusic
• mFiles
• Jacco Eerland's sheet music
• list of Negro spirituals
• Hymnary, a database of hymns searchable by text, hymn tune name, and scripture reference
• International Music Score Library Project
• Chordie, guitar tabs, chords & lyrics
• The Untraveled Road Music Collection of Kelvin Smith, a collection of choral, piano and organ scores
• Free sheetmusic, a collection of organ, piano, chamber and orchestral music
• IN Harmony, a collection of sheet music available through the Indiana State University

• Finale, the de facto standard for music notation and typesetting (they also have a smaller, simpler, free version of the program called NotePad that is available for download).
• Cakewalk, a MIDI sequencing program.
• Power Tracks Pro, a great, cheap sequencer/notation program - only $29.95!
• NoteWorthy Composer, an inexpensive music notation program.
• QuickScore Elite
• Audacity, an open source audio file editing tool.
• CDex, an open source CD audio extractor application.

Synthesizer patches, samples and libraries

• Creative Labs, the makers of SoundBlaster
• Harmony Central
• Keyboard Magazine
• Music Machines, good source of samples, patches, MIDI files, synthesizer documentation, etc.
• Synth Zone
• UCSD Syntheziser patch library

MIDI references

• Cyber hymnal (MIDI files, lyrics and other info about non-copyrighted hymns)
• English folk music
• Christian MIDI
• Classical MIDI Connection
• The Episcopal Hymnal
• HymnSite, MIDI files of hymns and psalm tunes from the 1989 Methodist hymnal
• Lutheran MIDI hymnal
• MIDI hymns
• Praise & Worship MIDI
• Seventh Day Adventist Digital Hymnal
• Silvis Woodshed (choral related MIDI files)

Sources of music and instruments

• J.W. Pepper
• Lark in the Morning, a music store specializing in unusual musical instruments