Naxos is a pretty familiar name to most musicians and music teachers, but for some reason I had never visited the site. I came across it in a recent search for information on an obscure composer. I was amazed at the exhaustive list of both composers and artists. There are portraits and brief biographies for hundreds (perhaps thousands!) of composers. The design of the site is very user-friendly, allowing for a quick search or browsing alphabetically by last name. You can also browse the artists by instrument or position (i.e. conductors, ensembles, orchestras, choirs, singers, percussion and narrators).
What a fabulous resource! I only wish I had come across it sooner. 🙂