How to use and bias LM285 shunt voltage ref for virtual ground?
Turns out to be dirt simple.  You put a bias on it calculated so that any additional currents going through it don't take is outside of the operating range.  For example, when using it as a Vref input for an AD623, the source impedance is 20 kohms, and when powered off of 5 volts, the maximum current injection is 2.5V/20 kohms in either direction. or 0.125 ma.  When using it as a virtual ground on an inverting op amp, we're talking about bias currents.  The LM285 wants at least 10microamps through it, and can do 20 milliamps, so placing a bias of 500 microamps would put it in its operating range, and when using it for the AD623 Vref and a few inverting amps, there's nothing you can throw at this reference to bring it below 10 microamps of operating current, so you're good to go.