One of the most useful products I've used this season past is Loon Deep Soft Weight tungsten putty.
It's very dense and heavier than lead and so a little will go a long way.
It's very quick to add and remove meaning your flies spend more time in the water rather than your hand.
Unlike shot, it won't damage your leader, is non toxic and biodegradable and once set correctly won't move around on your leader nearly as much as shot. It won't hang up on rocks popping your leader and is reusable so a container will last a long time.
Carrying Deep Soft Weight lessens the need to carry too many flies of varying weight: a pinch of putty will drag your pair of small 18's down to what is normally the realms of the larger bomb.
Trying to get that buoyant egg pattern down this winter? This is your answer.
On colder days I keep my pottle in an inside pocket to remain more pliable in the warm, and more exposed to the elements in normal conditions. Simply pull off a pinch, roll between hands to soften, apply to leader and dip in the water to cool and set.
I prefer to apply putty in an elongated shape on the trace inbetween my nymphs when possible, to keep them both down in the zone or several inches above the top nymph when fishing minimal trace between my flies.
So bombing glo bugs on the Big T or needing to get that tiny nymph a little deeper for that choosy, spring creek brown, Loon Deep Soft Weight is a handy tool to have on hand.