How about doing a mock dubbing where we actually experience what a VA may have to go through? Like just throw a script at us and say "you are going to be voicing X." Following along with this line of logic, assuming you are bringing more than just one person, why not have them all voice a whole episode and include it on to a release (or to just those individuals) as an alternate take?
I second that, and I'd add the possibility to choose any episode/part of any serie licensed by Funimation.
I'm not sure about including it in an official release but at least returning home with a copy of the resulting video would be nice.