So here's my current set-up for brainstorming:
* I have a nice red binder filled with lined paper and dividers to add notes, ideas and such into. I'm going to make a few "pocket" pages to keep little articles or pictures or stubs of paper I might use on a whim to jot an idea down. (Making a pocket page is as simple as taking a piece of paper, folding over 3/4 of the page and either stapling or gluing it to make a pocket.)
* I have my favorite red little LuLu Lemon gift bag that holds all sorts of stuff like colorful highlighters and pens, paperclips, books I use for reference and such.
I assume eventually I will graduate to a bigger bag and a few more binders or journal books to write in as more ideas come to mind, but for now what I have should work out just fine.