I like the InfoGraphic at…
http://www.informationisbeautiful.net/2009/if-twitter-was-100-people/
It helps us put Twitter, one of the world’s most popular social networking sites, in perspective. For example, you’ll notice right off the bat that, if the Twitter community was 100 people, 20 would be dead (empty accounts).
I notice the graphic is dated July 2009 and wonder how the data have changed in the ensuing 5 years.
Very much worth noting how old this graphic is. And it is also worth noting that you should consider the audience you are trying to reach. Twitter gets high usage in some countries. Here in the U.S., Twitter’s own research has concluded that Christian leaders are among the most active users on Twitter. Definitely do more research before discounting Twitter too much.