Great discussion! I recently have been working on a tune with such a chord.

It moves from Bb to Bb/b5 to Bb. I think this middle chord sounds best as Bb D E.
On my Tyros screen it shows up as Bbb5

[Dm]I wonder as I [Gm7]wan-[Gm6/7]der [Gm7]out [Am]under [Dm]the [C]sky

[Asus4] How [Dm]Jesus, the [Gm7]Sav-[Gm6/7]ior, [Gm7]did [Bb]come [Bb/b5]for [Bb]to [Dm]die.

Jay R