We get asked to do virals a lot. And we seldom deliver because usually we get asked to be "on brand" and place a logo at the end and do just ONE thing. Truth of the mater is that, today, virals are like games that you engage the consumer in, so sometimes you need to build more than one thing.
The funnest 'game' I got involved in recently is this post by a careless Romanian blogger. As Romania is hosting a NATO summit and tension is high [as is security level] he made a joke about renting space for snipers on his balcony. The fun stuff is that all the people who joined the prank played along and if you click on the names of those who replied you will be taken to a fake CIA page (real one is cia.gov BTW), a fake AlQaeda page and even an AlQaeda manual :-)
Everyone played along and this made it interesting...because virals need to be engaging and interesting :-)
communication is essential to business making and it involves more than the ability to name your product, write a tag line or a press release. It's an intricate, rational and scalable effort and, let's face it, not anyone can do it.