Awesome ideas, man. That Reverse 450 you mentioned is called "The Imploding Star Press" I think. It's probably been done before, but I'd love to see a move that I would probably call the Shooting Star Senton. You start off on the top turnbuckle (or where ever the move is being performed from), facing a downed opponent. You then jump off the turnbuckle flipping backwards 450 degrees so that you land on your opponent in a senton bomb.
The STO stands for Space Tornado Osawa (I think), and it is when you have your opponent standing in front of you, then you kick one leg out from them while hitting them with a hard clothesline. Brock Lesnar did it for a while from memory, and Kenzo Suzuki does his variation where he puts his hand on the opponent's face, pushing their head back once he's taken a leg out from the opponent. I like to call it the "Bronze Claw".
Here are some more ideas for moves, I'm not sure if they've been done before, though:
Cartwheel Bodybreaker
The performing wrestler is facing their opponent (it would probably work better if they were doubled-over like the set-up for Booker T's Scissors Kick). The wrestler hitting the move cartwheels over the opponent, catching them in a headlock on the way over, landing in a kneel-out position, which would end-up like Randy Orton's move (I'm not sure if it has a name, or if this one is currently in use, but I like the term "Bodybreaker" for that type of move) where he snaps the opponent over his back.
This would look phenominal from the top-rope, and would make a great finisher for a cruiserweight.
Reverse German Suplex
There is a move called the "Northern Lights Driver" I think. I'm not sure what the move is, but I have a feeling it is much like the one I am about to describe.
The performing wrestler locks an opponent as if going for a belly-to-belly suplex. He then lifts the opponent, but drops them on their head/neck ( much like a German suplex-style effect). If a wrestler like Chris Benoit could roll these.....

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Full-Nelson Vacuum Cleaner
On SmackDown! Danny Basham took advantage of Rey Mysterio being in a wheelbarrow position, by slamming him down in what I can only describe as an inverted pancake. I don't know why, but I keep thinking "vacuum cleaner" would make a great name for this move. It has the blowing motion of the wrestler using great force to slam the opponent down, and it has the sucking motion of how the wrestler taking the move must suck up their gut afterwards. It just seems fitting to me.
Anyway, I've seen this move before, and I think it made its way into Billy Kidman's moveset for a while. Anyway, image this move with a full-nelson applied. Or maybe even a half-nelson where the performing wrestler uses the half-nelson to "weigh" the opponent over into a reverse prawn hold/clutch pin. I don't think I described that well, but anyway...
Pop-Up DDT
The performing wrestler has their opponent in a front-facelock, then they fall back into a bridge, driving the opponent into a DDT. From there they can pop-up with the opponent still in the facelock, then they can hit another one. Repeat at leisure, or they can turn it into some kind of choking submission.
Dragon DDT
This would be a good move for one of those "the opponent has put their head down looking for a back body drop but did it way to early" spots. The wrestler performing the move has the opponent bent over in DDT position, and from there they hook the arms in a fashion that would set-up a backslide. They then drop in a weight-added DDT.
Dragon Bridge DDT
The performing wrestler has their opponent in a wheelbarrow. They then lock in a standing dragon sleeper (that in itself would make a great move). From there the performing wrestler can turn it into a revrse brainbuster style move, but I'd LOVE to see them fall back in a bridge like move (or just in a flat-back, blasting the opponent with a high-angle reverse DDT.
I could go on all night lsiitng high impact moves. Like a Gory Special STO and stuff, but I'm too tired right now, but anyway keep those moves coming.