Always carry a small baggy of chum (loose uncured salmon eggs).
A little bit of candy thrown in the pool will usually garner a hit or two.
Many guys overdo it though, throwing ridiculous amounts of roe in the water.
Less is better.
If you think there's 10 fish in the pool, throw 10 eggs. Good rule of thumb to follow.
It's not something I personally do a lot of, but it's a deadly effective tool to have in your arsenal for those times that warrant it.
Once you've chummed follow it up by drifting either a single egg or an egg imitation.