These things were interesting two years ago but at the end of the day it looks to me like all the client wants to do is keep making TV commercials.  The fact the Internet has been a means of free distribution is beside the point.  It's just a TV commercial and sometime they are interesting and sometimes they are not.  The free distribution offered by the internet is to the most part less targeted than a TVC so perhaps that is why they have never really been able to tie these ads to sales.  

I suspect tomorrows consumer finds "send to a friend" horribly uncool.  My kids won't send anything they'll post it to My Space and see who cares.  I suspect the viral days are over for all but the best and it seems to me that is as much about luck as it is about skill and a finely honed brief.  I've yet to see a viral succeed that started out as a viral.  The last Big Ad started as an ad the viral thing was a happy accident.  We all remember the fighting bear thing from John West - same story.