Great thread. The way I cured my slice was to adjust my hip movement at the beginning of the downswing. Ideally I want my upper body still facing a little bit away from the target when I drop my hands on the downswing. But my lower body is much stronger than my upper body, so when I fired my hips to face the target on the downswing, they went too quickly. My upper body was facing towards the ball when I was lowering my hands, so the only thing I could ever do was "come over the top" and swing outside-in and cut across the ball.
So I slowed my hips at the beginning of the downswing, which allowed my upper body to face somewhat away from the target when I dropped my hands, and now I swing on the correct path when I make contact.
The way I slowed my hips was to have a lateral movement/bump/slide/move them towards the target at the beginning of the downswing without them spinning towards the target very much. And then after that bump, I can spin my hips as hard as I want and my swingpath is correct.
This "2 speed hip turn" is my swing thought on just about every shot unless something unusual has been creeping into my swing.
By the way, here is a helpful video that demonstrates this, as well as having a wonderful drill:
Hope this helps. I'm really excited about my game now, and can draw it, fade it, hit it straight with any club in the bag.