The "blending modes" available in the layers really do open up the possibilities for making some interesting textures...

the "darken", "multiply", "color/line burn" ones darken the underlying image

the "lighten", "screen" "color/line dodge" ones lighten the underlying image

the "overlay", "soft light", "hard light" ones add contrast to the underlying image

the "difference" and "exclusion" ones apply certain qualities of the active image to the underlying image

EXPERIMENT and have a blast!

:)