This is one for the nerds out there – let me hear you scream! – here’s a very comprehensive list of Graphical User Interface (GUI, pronounced goo-ey) prototyping tools.

So what use could they possibly have? Well, consider that you’re working on a sign up screen for a website or an e-commerce application. You need to test various versions to see how your users respond. The sign up page is a key conversion page and it pays big time to sweat all the small details.

In the design phase to build each full version is a lot of designer and programmer overhead. Building mock ups or prototypes makes tons of sense. You put the mock ups in front of some prospective users and get fast feedback. You take that feedback and roll it into the next designs, et cetera. The feedback loop makes for quicker mature designs that work for people, which is what matters.

For those of you not totally geeking it up with desktop drawing programs, I recommend the cutting-edge technology of the pencil and paper or the whiteboard. Both offer instant visual outputs, sharing, collaboration, extensibility and iterative versioning. Additional users can be added with minimal gains in overhead. Both also work across platforms and without electricity.

Best of all you get to wave your hands, point at things and scribble all over things, in real time. A great addition to communication is gesture, so don’t how back. Get your hands dirty and wrestle with the screens.

See how cool low tech can be?