Don Dodge discussed the very small percentage of content creators versus viewers:
in a group of 100 people online, one will create content, 10 will "interact" with it (commenting or adding to it) and the other 89 will just view it.
True enough. However, it's important not to discount the value of "just viewing". Viewing is an expression of attention, and attention is an immensely valuable metric to track. View and click data, for example, play a significant part in how Google/Yahoo/etc rank their search results - the more users click on a given item in the search results, the more prominent rank it gets in the results.
Consider a list of 100 random headlines pulled from random news sources. Consider 100k users viewing those headlines and clicking on the ones that interest them. Immediately you have a system for finding the most interesting stories of the day, simply by tallying which headlines get the most views.
A big part of the power of the web is the latent data that can be gleamed from the day-to-day, non-explicit actions of the masses. Content creators create obvious value, but lurkers and viewers play a vital role in unlocking, exposing, and magnifying the value of that content.