> take an USB or ethernet driven IO board with plenty of output pins,
> like the gluion (http://www.glui.de/).
> arrange the coils on a 16x320 matrix, wire 16 pins of the board as a
> bus of width 16 along the rows of 16 coils,
> and use the other pins ot build a 1 out of 320 selector, which you
> use to strobe one out of the 320
> rows of coils. you can use D-latches that only respond to the bus
> when strobed.
That is definitely the way to go - I typed out a huge reply about a week ago, seems it didn't get through.
The process described above is often referred to as a scan-matrix or scanning matrix. The "d-latches" are usually simple diodes. As stated the problem is one of scale.
Wiring and soldering a matrix of ANY size can be a hassle... You can drastically reduce the number of required pins by making a more symmetrical matrix, such as 96*96, or in your case 72*72 will give you the outs you need in a matrix, so "just" 144 outputs...
Still, the trick is wiring two cables plus one diode for each coil. That would be (16*320)*3 solder points. if soldering one point takes ten seconds, and prepping cables * 2, drilling hole and mounting the coil each takes ten seconds per coil, then your looking at 16*320*7*10(?) seconds - roughly 100 hours of labour. If you're a team of people then that's totally achievable.