These are amazing! One thing I'm not sure of; how do you mean "brushes?" I'm thinking of that in some sort of graphics program sense, whereas these seem more like graphics to be added to an existing project.
Great stuff, altough in my oppinion, i think that number 3,4,5 and 8 from the top are a bit too 'noisy'. There's just too much going on in them. That said, they're all great designs, and my comment only reflects my highly personal oppinion. I jus' like'm simple is all.