OMZen - 4:39 pm on Feb 13, 2010 (gmt 0)
AFAIK, there's no "full proof viral marketing" formula :)
Actionable items would be:
List all the segments of your target demographic
Identify the online places where they hang out ( Facebook /groups? Twitter /lists? , YouTube? , Ning ?, Digg? SU? some popular blog ? etc, etc )
Identify the top influencers / power users leading those communities
Get on the radar of the influencers ( further their cause for a sufficient time - reach out to them - pitch last )
Easier said than done if you are not a heavy hitter on the social scene, but if your content is truly purple and you can get the power users to talk about it - you stand a good chance.
Best wishes for success!