Lower it an octave and drop the bass note, you get xx3200 : it's almost an F7M chord, but with a b5 in it. You can also do x33200 and it's an inversion of F7M(#11)
I like to use b9 chords in turnarounds like maybe E#9, A7b13, D7b9, G7 and resolve to Cmaj7Find me a couple that sound fun, I'm messing around and not coming up with much. I guess the question is more "what chords sound cool with a flat ninth", isn't it?
been using jazz-inspired shell chords lately - 7 chords with 5th removed from them. so e.g. :
8x88xx -> x878xxx -> 6x77xx would be a 2-5-1 progression in Bb major.
Man, playing those voicings I realize how much I prefer playing chords that don't have too high notes in them. At least in most cases... I guess a dissonant chord with lots of distortion sounds extra jarring when you play it high up there.