This is follow-up to @Erik's answer to the question Is artificial gravity feasible in manned long-term space exploration? I'm curious, whether there's any alternative methods to simulating effects of gravitational acceleration as felt on Earth (9.78 - 9.82 m/s2), if there's any ongoing research, or proposed methods of achieving this? Could, for example, dynamic principles of a gyroscope (i.e. powerball) be used to create equally distributed centripetal force on the whole inner spherical body of a space station? Could such rotation on all three axis be sustained with inertia?
I don't want to limit my question to artificial-gravity only, but would also like to know of possible ways to actually create long-term sustainable gravitational fields, be it directly by producing gravitons, or by other ways of producing gravitational effects of a large mass body with small mass bodies, if this is at all feasible (quantum mechanical black holes maybe?), and how far are we from seeing any of such systems demonstrated either on paper and/or actual model-scale systems?
I am not interested in infeasible far-out / fictional ideas, but actual scientific research in this area and pragmatics of proposed (if any?) alternative methods.