Pocket knife, Chapstick, phone. Wind checker usually ends up in a pocket on a stalk. If I'm on a longer walk I'll throw a bar in my pocket as well. I try to keep them on the lighter side.
I'm with the guys that keep the pants pockets empty. I dislike the feeling of having something in there when taking long uphill strides and pull the pockets right against my quads.
I usually keep my phone in the chest zip pocket of my jacket, other than that it all goes in the pack and belt pockets.