However, I'm concerned that transformers (at least the ones that I'm familiar with) only seem to work on alternating current. Would this mean that a gravity transformer would only operate on alternating gravity? If so, I imagine that might present a few problems.
Alternating gravity does sound tough but alternating mass flow - say a compressed (non-flammable) gas in a doughnut shaped pressure vessel, adorned internally with a series of electro-active baffles (Beifeld-Brown capacitors) along the inner walls and a rotating magnetic field going "round the outside!"- sounds almost doable, even on a budget. It's also starting to sound a bit dangery.
As for usage, while I love flying saucers, ray guns and boobs as much as the next nerd, I wouldn't want to see that much energy wasted to accomplish what could - in most cases - just as easily be done with solar powered dirigibles. I think the most believable application might be as a sensor. We might be able to build a small, stable transformer that would allow us to detect gravitational anomalies (as we fly over the land and sea in a solar powered dirigible). The same way we use a metal detector to find coins on the beach gravity transformers might allow us to identify various geological formations underground and greatly reduce both the economic and environmental cost of resource mining.
Ooh hey look I mentioned environmental cost reduction; I think that makes us eligible for a government grant! Who's in?