All of the above ... plus, "injecting" them into hollow tube jig bodies.
1Weezer (Richard Williams) puts a jighead on his line, then puts a plastic body on the jighead, then puts a minnow on, and caps it off with a "nibble" (I think that's right, correct me if not). He uses this "concoction" to slow troll with.
Casting with them can be a problem. This is where the Bait Pump comes in handy. It injects the nibbles into the hollow body tubes, allowing for longer use time .... and less "waste".
Otherwise, using them externally on a hook or jig, you want to allow them to dry out a little, first (before putting them on a hook) ... since, coming straight out of the bottle, they're a little soft, and fish can knock them off the hook and/or your rod movements can. You may even want to put them on the hook/jig, and allow them to dry ... meanwhile, using another outfit.
None of this info is from my personal experience ... just what I've picked up, here on the site. .......... cp