Here is a really fine online magazine devoted to American Opera.
Site leads to other kinds of arts resources as well.
These are useful pages for finding quick-reference opera information. You can also post to the list, and join if you wish. The Database includes the complete set of operatic arias of Verdi, Mozart, and Puccini as well as many others. Club Op ra - Great information and links, the site is entirely in French. In addition to English songs, there are Irish, Scottish, Welsh, Canadian, Australian, and South African songs.