You could try ultimate-guitar.com. They have a lot of threads for
all kinds of music. I did a quick scan and found Muse under Modern Rock

. But it's not just talk for guitar afficionados. Murmurs.com (R.E.M. fansite) used to have a good general music forum. They're forum layout changed a bit, haven't been there in a long while. One of my favorites thought I haven't visited in a couple of months is Bowlie.com. More so for the indiepop, twee-minded type. A good thing, mind. I understand what your looking for CP, a place to really discuss music, because it's really when I tend to post the most.
Good luck in your search, let us know what you find.
