A disk spindle motor has nice bearings and usually doesn't include the
multi-phase driver electronics, and so will make a fine (three phase,
usually) generator.  I even watched one do so on a scope recently, which was
pretty cool.  It's also designed to operate at moderately high speeds (3000
to 10000 rpm, these days?) so it'd be a good candidate for being driven by
an air turbine, I think.

BillW