One such technique has been aiki nage, as it's called in Tomiki aikido, or irimi nage in Ueshiba circles (although irimi can mean a lot of things, it appears, but I won't get into to that here). In fact, we had a lengthy discussion on the forum about why the name is different at all, but I'm not sure anyone really knows.
At any rate, I'll try to describe the way I've always been shown (sorry, I don't have a video). The arm position is basically the same--the main hand centered in front, the palm sideways, the elbow out, the whole arm in a curved shape. But at the point of throw-- after spinning uke around in one direction and then reversing that direction and entering--tori simply keeps his hand in front of him and spins backwards in another circle, and let's that circle get slightly larger as he goes (like an ellipse).
Well, that method has never felt all that smooth to me, but I'll be the first to admit, that this may very well be because I don't really understand it. The Ueshiba irimi nage, however, is more linear. The arm position is more or less the same, but the arm sort of rises and then, once past uke's head, dips down again.
Now, from what I can tell, most Ueshiba schools seem to love making this throw as dynamic as possible. Sure, it looks pretty when you send uke flying through the air, but I wonder if they're a little too intent and getting a large, acrobatic throw out of it. I think that maybe one reason for the large acceleration of uke before the throw. I've also seen variations where tori sticks a hip in there to add a fulcrum around which uke can spin.
A lot of techniques can be dynamic, really. I've had ushiro ate done to me where my feet have left the ground entirely and my body ends up horizontal. It wasn't intentional, but the circumstances were just right. And it was all my doing, not tori's. He wasn't trying to get a big air fall out of it; we was just setting up a condition. My own, shall we say "enthusiasm" as uke prompted a more dramatic fall than the standard sit-down backfall.
Conversely, kote gaeshi doesn't have to illicit a large flip in the air. Tori simply sets up a condition; maybe uke flips, maybe he sits down. I think the moment I start thinking I have to create an acrobatic fall, I start adding energy, trying to dictate when the throw happens rather than let uke throw himself, or heaven forbid get ahead of him, and well, that gives uke plenty of opportunity to reverse the dumb thing on me.
Back to irimi nage. I've been playing with entering the way our Ueshiba brethren do it (and many times including the use of the other hand in the small of uke's back as in the video above, which works wonderfully). The one thing I don't do is try to make a throw. Rather, I just keep moving (stopping your butt is a common side-effect when trying to make a throw happen, one that can also lead to problems). If I simply set up the condition, and keep walking, always matching uke's speed, he finds he just can't walk backwards while his spine is bent back very efficiently. My hand doesn't push down, but simply lowers a little bit with every step uke takes. Light, no effort, uke falls in a nice sit-down backfall.
Not very flashy, but so far, it's been rather successful. I'm not saying that it's right or better, or anything. Just another interesting pit stop on my journey.