I have been getting a lot of campaign fliers in mail and on door knobs. Many of them this year are on glossy coated card stock. I keep a good supply of that kind of card stock. I cut it up and put it in a drawer by my work bench.
I use it for two purposes. First, for CA glue. I put a daub down on a piece of card, and use a toothpick to apply it to model, or just dip the end of a small part in it. For gel CA, even uncoated card works, but the regular (low viscosity) stuff soaks into uncoated cardboard too fast. But it works fine on the coated card stock.
Second, I use it when dry brushing. I wipe the brush against the card stock, then go back and pick up the semi-dry paint with the brush to rub it onto model.