You can get a magnificently large -- 4 by 8 feet --and fabulously cheap whiteboard for all of $13 at Home Depot

Kevin Kelly -- Cool Tools: "Turns out that brainstorming is an epigraphic activity -- something best done on walls. Reading and writing on walls is a different function than reading a book. A broad wall-view is an ideal approach for collaborative design -- multiple views in a single glance. Thus the tremendous interest in flip charts, graphic capture, doodling, giant post-its, whiteboards, and all the electronic equivalents of those. By far the cheapest and easiest epigraphic display is a large whiteboard. And when it comes to whiteboards, you can't be too big."