Y'know, shields are wonderful things. One thing we have never seen anyone use them for, however, is lift-off.
Inspired by Buckminster Fuller, I was thinking the other day of using shields in a Cloud Nine fashion, making a big enough shield bubble to let minor air temperature changes float the ship.
But, vacuum would work better, even if it was a bit more taxing to the shields due to pressure difference. Start with skin-tight shields and then expand them outward laterally and upward, leaving a vacuum in their wake. At a quoted lifting force of 1.28 grams per liter (based on the displaced mass of air at sea level), my math suggests that a 700,000 tonne starship like Voyager could be lifted by a vacuum volume of 546,875,000 cubic meters.
That's a sphere of 1,014 meters in diameter, or a hemisphere of about twice that depending on how you fit the ship in exactly.
We have seen the Enterprise extend shields to protect a ship at a stated range of five kilometers, IIRC, so in principle it might be doable. And that doesn't even bring subspace mass-lightening into the equation.
Certainly it would be an interesting way to soft-land a starship rather than crash*, assuming you can figure out how to drop the shield gently on touchdown. I can't imagine a sudden shut-off, producing a mad rush as air tried to fill a kilometer-wide void, would be healthy for any ship that needed to be using the technique in the first place.
(* In the case of the E-D saucer, of course, it seems this wouldn't be useful as the shields did not seem to be online. )