Manipulating Gravity (For Fun and Profit)

Anti-gravity and artificial gravity* technologies are staples of far-future and space-set sci-fi. Even if it's not explicitly stated, it's there whenever people walk on space stations, tow anything under their ship, or fly their car into the sunset**. It's been used so often that some people would say it's nearly cliché.*** 

I'm inclined to agree—to a point. The gravity applications in my first list are great, even if common and largely in the background. I think they probably will (and probably should) stay that way, unless there's a really brilliant unwritten story out there that uses them as a major device. But, and this should come as no surprise to regular readers, I want to see the boundaries pushed. What else can we do with technology that manipulates gravity?

(I feel I should warn people: I've been reading in the Vorkosigan Saga**** by Lois McMaster Bujold lately and this is necessarily going to influence my examples.)

6 Fictional Things We've (Over?)Done With Gravity Technology

1. Earth-gravity on spaceships and space stations - This one's pretty straight-forward. If people are walking normally while in space, it's because a) they can manipulate gravity or b) they're really in Hollywood.
2. Anti-gravity spaceship propulsion - This one too. Usually it involves spewing out gravitons or pushing against the gravity of a planet or star.
3. Flying vehicles - Again, straight-forward, and using the same ideas as for spaceships, as far as I know. This doesn't just go for cars or intercontinental vehicles: the Vorkosigan Saga has float-chairs. (I'd also like to point out that Back to the Future II is set in 2015 and has flying cars in it. The clock is ticking.) 
4. Tractor beams - The technical term for those rays that shoot out of spaceships to catch other spaceships, causing dramatic tension and endangering the heroes/villains. There are probably ways to pull this off without anti-grav, but messing with gravity in a localized area is probably the simplest.
5. Weapons - Granted, I haven't seen this lots-lots, but it's out there, blowing up (or imploding) things. Again, a Bujold reference: the latest in space combat is the gravitic imploder lance. It does really nasty things to spaceships.
6. Forcefields - Another could-be, could-not-be anti-gravity application. Usually I see a plasma screen of some kind, but I can definitely see anti-grav functioning in this capacity. Nothing would penetrate a gravity wall because everything would bounce away.

6 Fictional Things We've Underdone With Gravity Technology

1. Colonized planets - There are a lot of exoplanets out there, but very few are going to have Earth-like gravities. Therefore, being able to manipulate the strength of gravity will prove useful in forming our galactic empire. We can make low-grav planets "heavier" around our colonies, and high-grav planets "lighter", and gravity forcefields could be used to keep the atmosphere in inhabitated areas. We should also be able to use a combination of these technologies (and basic "hovering" anti-gravity and general spacecraft building) to form colonies in the dense atmospheres of gas giants.
2. Colonized oceans - See above, except in the Marinara Trench.
3. Non-Earth-gravity on spaceships and space stations - Because not every alien species is going to come from an Earth-gravity world.
4. Utilitarian tractor beams - This is something I've seen in Bujold's work, but nowhere else*****: portal tractor beams used to dig holes, haul prisoners without cuffs, dredge lakes, etc. I'd like to see more of it, or a story where these utilitarian beams are the only ones and we haven't perfected ship-hauling sizes of them.
5. Clean energy - It should be possible to set something spinning in a null-G vacuum chamber and use the spin to generate power. It wouldn't be a perpetual motion machine, but it would probably get close.
6. Dieselpunk spaceships - Based on the "gravitator".

6 Stories Using Gravity Technology

1. The anti-grav mechanism on the Ford Nebula tends to fail at inopportune moments. Is it a fault in the technology, an oversight in the engineering, or is it deliberate? 
2. An intrepid first-contact team encounters a trading fleet that proves to be friendly, but comes from a low/high gravity planet. Major diplomatic problems ensue when the members of one race board the other's ships and fall ill/can't move/get crushed. 
3. The null-G vacuum turbine is now cheap enough to be purchased en masse by developing nations. How does access to cheap power transform their societies? What applications do locals apply it to that more technologically-advanced nations miss?
4. Earth, 1950: gravitators become strong enough to lift large vehicles just as the Cold War is beginning. Nuclear fusion proves to be enough to power intercontinental vessels and/or spaceships. Does America co-operate with the U.S.S.R. and head for the stars, or does the technology become just another part of the arms race?
5. A salvage team is sent to a recent deep-sea wreck to recover everything they can, but discover that the wreck holds a secret….
6. Before the colonists settle 55-XB-194-alpha, they need to set up the gravity dome. This proves more difficult than expected because of natives/wildlife/geology/ruins/malfunctions/etc.

(I'd like to thank WikiCommons for providing today's images.)

* technically nearly impossible under general relativity, since gravity now results from warping space and no longer involves gravitons, but who's listening.

** usually, for that last one

*** I don't know these people, but as there're folks who'll argue or dismiss anything, it's safe to say anti-grav detractors exist.

**** Fabulous witty space opera series. Read it.

***** Not that I've read a ton of sci-fi, so maybe I've just missed it