One of my friends wrote an excellent article on Wireframing
with Fisher Price.  The idea is that you can use a child’s toy (similar to
an Etch A Sketch) to wireframe effectively.  I believe the most important theme
he captured was:

No detail – It’s very hard or nearly impossible to put any type of detail into
these drawings. In some parts of design, detail is very important, but in wireframing,
detail can be the downfall of the process.