We tend to really like paper prototypes in our line of work.  We often find that by just doing three or four prototypes that we have significantly increased our knowledge of what the client needs up front.
Techniques and tools are discussed at introspectiveH.

As we look to start conducting usability tests, we need to make sure our toolkit is in place and ready. The ability to deal with video and audio recordings is getting simpler as well as the ability to combine them.
This is a small inventory of what is required for a portable usability lab: