There are a number of websites that I think it's worth calling attention to. Most of these are pretty recent and will be quite useful and informative. Mazal tov to the publishers!
Save The Music.com: Jewish Songs: Yiddish
SephardicMusic.org
Der Yidisher Gramofon
Finally, George Robinson, who many will know as the music critic for the NY Jewish Week, has started a Jewish Music blog, Shirim Khadashim -- New Jewish Songs. He will be posting reviews and other music-related writings, since the JW no longer has the space for his review column.
