Scoble has some interesting thoughts about what works and what doesn’t in viral marketing. Worth a read.
I have to agree. Without saying anything that might get me fired, anyone involved in creating virals, particularly in the brainstorm and proposal stages, ought to read his list.
Just because you call it a viral does not make it one. Sending it to hundreds of thousands of people also does not make something any more viral, it just annoys more people.