I think there is a 'Tourette Syndrome' option! Found these as well

http://www.nav-voices.co.uk/Scripts/prodList.asp?idCategory=72&gclid=CNamoJ--0ZgCFQaA3godej2T0g

'Problem' on new unit is that not evey voice supports the TTS option - but think I may have to buy a few just for variety. The Yoda voice does rather appeal!