Websites devoted to bringing musicians and music-lovers together.
NewMusicBox is an online publication by the American Music Center, devoted, unsurprisingly, to new music. Their definition of "new music" is admirably broad: nearly any musician who considers what they do to be "new" is in. Uptown, downtown, jazz, indie rock, folk music -- they all have their place at NMBx. Unfortunately, their focus on American music -- after all, it is the American Music Center -- sometimes feels short-sighted, despite their similarly broad-minded notion of "American".
Sequenza21 calls itself "the contemporary classical musc community," which is an accurate description. Its contributors include composers, performers, and music enthusiasts, giving a wide range of viewpoints. You can find news articles, concert and CD reviews, discussions, individual blogs, and more at S21.