Good ideas, serenbat, I hadn't thought about bringing them water. That is a definite can do!! I also have some winter items I plan on donating to them. :-)
bring water! even in an old jug for hand washing - offer to take back things that need washing
a thermos full of tea or coffee is always appreciated!!! or ice if you are in a hot area
we do bring lots of snack food (besides other items) - popcorn is cheap and easy
can you make copies?
have extra items that they might need? just ask
main thing in our area is to spread the word- letters to the editor of your local papers are FREE!