I'll keep a master list here, incorporating any submissions posted below.
- Mudcatter Liland's Esperanto hym site
- http://www.hymnsite.com/ (United Methodist)
- Southern Gospel Links
- Fasola Home Page (Sacred Harp)
- Southern Harmony and Musical Companion - one of my favorites
- Oremus Hymnal (Anglican)
- http://www.lutheran-hymnal.com/
- Project Wittenberg (Lutheran)
- 1912 Lutheran Hymnal
- Pentecostal Online Hymnal
- http://www.sermonaudio.com/hymnlist.asp
- http://www.ehymnal.com/
- Seventh-day Adventist hymnal
- Worldwide Church of God Online Hymnal
- Hymnals of the Stone-Campbell Movement