1.
AMG's All Music Guides
A complete site with information about all types of music, styles of music, the history of music, key artists and key albums. Searchable by artist, album, song, style and label.
2. Andante
This site is intended to document and preserve the world's recorded classical musical heritage and to become the definitive online resource for information about classical music and opera.
3. OperaWeb
The starting point of opera on the web.
4. Ultimate Band List
A complete guide to albums, websites, and concert schedules for your favorite performers.
5. The Tower Records Searchable Catalog
Tower Records is one of the most well-known music retailers in many parts of
the world. Its searchable catalog provides access to a potentially useful
reference tool for music related queries. It contains two advanced search
interfaces, one for all types of recordings except classical and the second,
a specialized classical interface. Search by composer, artist, album title,
and more.
6. Worldwide Internet Music Resources (Indiana University, School of Music)
The most comprehensive list of music resources. The list is not annotated.