A stinger hook on your biggest and bushiest jigs might help on those days when the fish are just nipping at the tail and not getting the main hook. That's more common with smaller rainbows than with big browns, but it can be frustrating...especially when strikes are few and far between.
Most serious bass chasers keep a supply of stinger hooks in their tackle boxes to add on to jigs, spinner baits and buzz baits for the days when the bass are being tentative. They will all tell you of times when every fish they brought in was hooked only on the trailer hook. I've seen it work the same for trout and other species too.
If you pinch the barb down on your regular jig hook, you can put it through the eye of almost any of the "ring eye" type hooks. You will need to follow it up with a small bit of rubber band...or piece of a plastic worm or something to keep the stinger hook from easily coming off...especially during a fishy confrontation.
Hook manufacturers have responded to the occasional need for an add-on stinger hook, by making some with a larger ring eye. One of these is the Mustad 3366A. Many full-line tackle suppliers carry them, but I buy mine in several sizes from Janns Netcraft http://www.jannsnetcraft.com
The example in the picture shows a hook similar in size to the main jig hook. Sometimes you can use a larger one. Other times only a smaller one is necessary to get the job done. It should extend only far enough to hook the fish, and not so far as to interfere with the appearance or action of the jig.
The good thing about these hooks is that there is no complicated tieing of connecting line or leader between main hook and stinger hook. But, even if you do not pinch down the barb on your hook, you should add a small piece of rubber band or plastic worm to anchor the stinger in place. A bit of bright red or chartreuse plastic...or even one the same color as the jig fibres...can sometimes add extra attraction.
Since the hook swivels freely on the shaft of the Jig hook, it does not impede action. In fact, I have strung several successively smaller hooks, in a "daisy chain", to fish large strip baits or big crawlers. How 'bout dat?