Just discovered this great tool while attending a Web meeting organized by Care2, the leading green online community. The ROI Calculator for Social Network Campaigns lists all steps you can imagine that marketers need to take when setting up an area in a social network. It adds in the dollar and time costs. Most importantly, it looks at conversion rates.
Gathering up 'x' number of people online is not enough. The important question we need to answer is how many people among those recruited actually donated, signed up, purchased or took some sort of action.
Two small additions I'd like to make to the calculator:
Member lifetime value - We also need to think about the lifetime value of those who take action now and those who are likely to remain engaged and take action in the future. ( I believe this is what the authors call 'investing in the future.')
Online real estate value - When an organization builds a social media hub and continuously works to keep it up to date, it rises in search engine rankings and reaches increasingly wider populations over time. The social media site becomes an evergreen investment.