Moderating focus groups can be challenging if a concept does not generate a lot of dicussion.  Sometimes respondents are not that familiar with it or have a hard time understanding how it could be used.  In these cases, a useful focus group technique is to have members of the focus group "sell" the idea to other members.

Divide the group in half and have one half work as a group to come up with several reasons why the other half should purchase or be interested in your concept.  The other half of the group listens and counters with why the other group should not purchase the concept.  Each group is also allowed a rebuttle.

Selling a concept within members of a focus group is a great way to get respondents involved in the concept.  They have to understand it to be able to sell it.  As a bonus, it can deliver what's important about the idea, what are the hot buttons and holes of the concept and general fodder for further questioning during the rest of the group.