Composers:

AMIC - Archivi della musica italiana contemporanea by CIDIM, Roma
A database of Italian contemporary composers, with addresses and list of works
Biografie compositori at Karadar's classical music world
Biographies and lists of works with MIDI examples and texts of some works
Archivio di musica contemporanea by Marco Russo, Università di Trento
Info on composers born after 1946
Composers at the William and Gayle Cook Music Library, Indiana University School of Music
A list of over 200 composers and composers list websites
Dizionario della musica e dei musicisti dei territori del Ducato di Parma e Piacenza dalle origini al 1950 by Gaspare Nello Vetro
A dictionary of all musicians related to the Parma and Piacenza area
Donne musica
The website of women in music
Les dossiers compositeurs contemporains, at IRCAM, Paris
More than 3300 contemporary composers with biography, list and details of works, etc. in a searchable index
Electronic Encyclopedia of Composers by Germano Rossi
A list of better and lesser known composers with biography and list of works and some external links
Festival of European composers
News and ephemera on European musical life
Fondazione Adkins Chiti: Donne in Musica
International Adkins Chiti Women in Music Foundation, member of IMC - UNESCO
Gallica 2000 at the Bibliothèque Nationale de France
Portraits of musicians of the 19th century; follow the link Catalogues and search the name you desire
Gaylord Music Library Necrology file
Dates of death of a lot of modern composers
Guida al Dizionario dei Musicisti Marchigiani di Giuseppe Radiciotti e Giovanni Spadoni
An index to the dictionary at the ARIM website, with bui-bibliographical data of composers from the Marche region
Osterreichisches Musiklexikon Online, edited by Rudolf Flotzinger
The online version of the Osterreichisches Musiklexikon
Music at Multnomah County Library, Portland, Oregon USA
Containing a list of links to the main composers sites
World biographical index
A comprehensive bioghraphical index containing 2,8 million short biographical entries
www.komponisten.at
Biographies and links to scores, posters, audio files