Great topic, and one that definitely has the mystique of fishing all over it. Clearly to Josko's point the use of poppers is waaaay easier on spin gear, and a great application for spin gear's advantages. Like BobP, I also love poppers on a fly rod 'cause they are such a blast to fish, and there's a challenge in putting one together that matches the capabilities of the flyrod as well as having a good popping action. A lot of the guys here have been making effective and amazing looking crease flies (see patterns). I tend to go with livebody foam, and I really like the ones with the forward flared cup faces because they cast easily and pop with little effort.
Once you get a good design or two together the next challenge is dealing with the intermediate line! I think I am finally going to bite the bullet and buy a SW bug taper line. They are great to cast and if I could fish the popper at the speed I like to fish them without worrying about sinking the line I would do it more often. The intermediate line makes me rush the retrieve a lot more than I like.
The times I do best with poppers are during slack tides or off-light hours when the visibility and added disruption helps convince fish to hit. I can recall a couple of holes where the fish lay during still tides. Somedays you can't seem to do more than urge one or two fish to inspect a fly fished subsurface whereas switching to a popper gets a committed and aggresive lunge from several feet down to attack the popper.
Also, blues are suckers for them and it's a great way to enjoy the bluefish battle on a flyrod.
Even with popper flies it's not automatic, they seem to be very selective about suggested color, profile and most importantly size. Any good spin popper guy will agree with you on that one, bass seem to be particular about the popper they will take often enough to be noted.
At this point I like a few popper fly patterns...
a) squid banger - extra large livebody foam cylinder, mill cup end using dremel tool and poke a starter hole with a large bodkin. Hook long shank humped Tiemco. Wrap hackles for legs and collar at base of legs. Underwrap thread and push foam over the shank immediately after a drop of zap-a-gap is applied. Wrap reflective spotted sticker sheet piece around the foam, use large eye near the base of the foam cylinder like a squid and coat with a thin epoxy coat.
b) Herring banger - Tie matched hackles like the juvie, upper flanks silver polar flash, top with baitfish back synthetic (durable). Set this part 1/3 shank toward eye from bend (or per preference). Cut large foam cyl with a vee groove in the rear to match tie-in point of baitfish body (above). Cup face with dremel. Underwrap and zap in place. Use bright reflective tape over body flanks, big eye in herring position and dark back. Draw dark dot behind eye at edge of gill with marker. Apply thin epoxy coat. This retains some profile even though it's a popper.
c) silverside popper - livebody foam flared to the front with scooped face (comes with hole). Hook 811s (short popper body). Tie transparent synthetic hair (bottom), silver polar flash (core) and light seafoam green synthetic fishhair (top) a little ways above the bend. Underwrap and thread popper head w/ zap. Cut a strip of reflective tape or the space between rows of sticker eyes and stick on each side of popper body. Attach a small eye like a S/S. Pantone olive / green back, coat with thin epoxy coat
d) sand eel slider / popper - hard to beat page's slim jim for a slider, but to get a better pop cut a thinner, longer livebody cylinder at an angle so that the 'face' is longer on top, shorter on bottom (like a classic bass popper). Hook 911s. Tie with a longer tail like the deep eel or according to your preference, poke starter hole using a large bodkin and slide over zapped underwrap. The body can be enhanced using a matched segment of body braid, which offers a number of flashy accents as well as some structure. Otherwise use either pearl tape or hold a strip of flashabou on the side while gluing like Page does to get that body shimmer. Use small yellow eyes, pantone back or use dark reflective tape for a back.
Caught my first bonito from shore on this slider / popper!