Peter, is there any hope for resurrecting the Crossbar? I think you said you're pretty busy these days, but I've been working on a similar device... it's an automatic circuit bending device I've been calling the Bend Matrix.
It's got a 4x4 matrix of lighted LED buttons, each which makes a connection between jumpers coming out of the Bend Matrix, using 4066 analog switches. the jumpers can be hooked up to "glitch" points on a circuit you want to bend. Press the buttons and viola! ciruit bending! possibilities include saving your patches, midi controlled bending, etc...
I've used it as an audio signal level switching patch-bay (ala Crossbar) by connecting the jumpers to 1/4" jacks, and it works but I get more bleedthrough than I want. I think a little resistance to ground on both sides of each 4066 switch would take care of this. Maybe buffering before the switches. Or different switches could be used (multiplexor, relays, etc)
Additionally (and this is where it gets fun for circuit bending, but perhaps too crazy for crossbar-ing) it has two a/d convertors (ADC0804) which take in a CV (provided by knobs or photocells) and output an 8-bit code. The two 8-bit codes correspond to the 16 bits of the 4x4 matrix of buttons. So as you turn the knobs up and down, the lighted switches flash in a binary counting sequence from all-off to all-on. lots of fun for glitching your glitches...
here's a rough wiki page (photo and soundclips)
http://www.commonsound.com/kits/doku.php?id=commonsound:bend_matrixBe interesting to see if there's any energy now for working on switching matrix/crossbar. I plan to develop a pc board/kit for the bend matrix for circuit bending, but if it can be a wider project, that'd be great
