Obviously, flight form is a great way to quickly escape any non-combat situation. Have you considered the implications of being able to escape life-threatening situations such as lava damage or other environmental peril? Peril such as the Aldor elevator? I think an advocacy group should be formed to deal with the one entity that claims more lives each year than PvP, Murloc, Hogger, and Naga-related deaths combined. Call me a lowbie, but almost everyone dies from that blasted elevator at some point. I guess it helps that I'm a scryer and our elevator is more survivable.
What about using flight form as a quick disconnect from any air-based crossfire from those on flying mounts? This may seem elementary if you've had flight form for a while, but to someone just getting it, it makes total sense. Jump out of flight form and you will begin to drop out of the sky, then switch back to flight form before hitting the ground, unless you like being a druid pancake. You are the only class that can flip in and out of flight form in mid-air at will. Imagine that huge draenai buddy trying to recast his gryphon before hitting the ground. Not going to happen. Now who's the pancake? This trick gives you the advantage in certain situations.
Druid-de-loop? Yup, all you do is setup a macro to /mountspecial and as long as you aren't moving (hovering for example) you'll do a loop. If you're wondering /mountspecial is the same command to make your character slide along the ground.
No turbulence. The airlines have nothing on us Druids, since mobs can still daze a 747 and send it crashing to the earth with nigh a thought, at least in Skettis (where anything is possible). Not for us, daze the mana out of us while in flight, and we won't even need a toothpick to recover. /rasp to you.
Skydiving, of course, along with the ever-popular game of chicken with the ground you can play. I prefer to call it American Eagle for some reason. Ever play that in gradeschool? Oh well. Trying to see who gets closest to the ground without splatting wins. Watch out for that server lag though, which can make sure the last thing that goes through your mind will be your rear end.
High altitude healing. Yeah, flipping out of flight form and healing yourself on the way down is a good way to get rid of DOTs, provided that you are high enough and can get back to flight form before hitting the ground. Might be tricky, but doable in a pinch. This can get you up to full health and ready for the next fight on the way.
Along with healing, you can also perform other interesting tricks, the first being the RAWRbomb. Shifting into Bear Form (or Dire Bear Form) and casting feral charge before hitting the ground can have devastating effects fon your unsuspecting victims. The second, the Stealthbomb (as I guess we are calling it, as of now) entails flipping to cat form and prowling before hitting the ground. That mob will lose his gizzard by an unseen force and you will be back in the air laughing about before he realizes you've also eaten his sandwich and left only the crust.
The safest place to AFK on the planet, or broken parts of whatever is left of the planet, um, thing. Enough said.
The Mary Poppins Special. I guess you could consider this the best way to uber-kite anything. With a carefully executed altitude changes, kiting becomes a simple matter of holding enough aggro, in competition with the latest episode of HOUSE of course. This could come in really handy when your group is trying to down a particularly difficult target, like that darned Fel Reaver for example.
You can also start the assault from the air, with instant cast spells, like Moonfire in particular. Maybe it doesn't help that much in the grand scheme, but it might just give you that extra fraction of a second, and perhaps a slight advantage. Perhaps more creative uses for air-to-ground combat will further extend this idea and make Druids even more powerful, versatile, and even harder to beat. Good for us.
What have you done with flight form that maybe we haven't mentioned? Please, enlighten us.