Recently I've been made aware of several music blogs new to me.
Mathemusicality is a new blog by James Cook, exploring advanced theoretic views of music.
Classical Convert describes Ben's new discovery of classical music, having only started listening when he was 23. He also maintains a larger website with advice for newcomers to the classical world.
the search for artistry is Phil Giampietro's blog on (duh!) the search for artistry in music. He's also a euphonium player.
The Sibelian Conspiracy is a group blog by composers to promote their music. There is some discrepancy in the mission, since the subtitle of the blog is "about music, art, and literature."