We use them all of the time and they are worth their weight in gold.
Anchor(can be a real anchor, stake or tree), snap swivel, a 20' length of 550 cord, a 10' to 20' length of bungee cord, 100' of 550 cord and a handle(I prefer a handheld extension cord keeper so I can roll the whole rig up on it). Have a few decoys rigged with 6" of line and a snap swivel. Tie a few loops in the main line close to the bungee cord to snap the decoys to.
Wade out, place the anchor(can be a real anchor, stake or you can wrap the 20' section around a tree and clip it), start walking back to where you are hunting from while unwinding the line, snap your decoys on the loops that you have tied, walk to the blind while unrolling the rest of the line. Give it a pull every once in awhile. When you are working birds only work it on the wingtips and tails.... just like calling. You can give it short jerks or even swim the decoys.
There are also other veriations as well but for on the move hunting like we do and putting alot of movement on the water this works best for us.