By Brute Force, I think I mean just incentivizing the audience in some way. The two most likely ways to incentivize are:

1. Monetary - Yelp paid reviewers a couple bucks a review. At Viximo we paid out guarantees. Glam paid out guarantees on minimum CPM's to early publishers.

2. Social Capital - From stories I've heard about LinkedIN, Reid Hoffman and early employees got friends to use the network and invite others.

3. Early Access/Coolness - You see this with beta invites, restricting early access, etc.