Erin Smith is a Senior Voice User Interface Designer and Usability Specialist with Syntellect (www.syntellect.com).Incidentally, people in the field use the word "vooey" - this is a pronunciation of VUI (Voice User Interface).Erin mentioned two books:"Voice User Interface Design" by Michael Cohen(www.amazon.com/exec/obidos/ASIN/0321185765/informdesign)."The Art and Business of Speech Recognition: Creating the Noble Voice" by Blade Kotelly (www.amazon.com/exec/obidos/ASIN/0321154924/informdesign).Paul English's "get human" website is www.gethuman.com.And here's a link to the episode in which I interviewed Donna Maurer on card sorting: http://uxpod.libsyn.com/index.php?post_id=126130Optimal Usability is the New Zealand-based usability firm mentioned (www.optimalusability.co.nz).This episode is 16 minutes 36 seconds in duration. File size is 9.5MB.