“Give me enough medals, and I’ll win any war.”
“A soldier will fight long and hard for a bit of colored ribbon.”
If you want to know why some people are able to achieve their marketing goals using social media, and other people are not, you should spend some time thinking about incentives. You can pay an army of bloggers to write about you, but once you stop paying them, they’ll stop writing. But if you survey your company / nonprofit / association, you’ll find employees / board members / customers who are willing to share their expertise in exchange for something other than money: recognition and respect. As long as you show sincere appreciation and offer public recognition to these volunteer writers, they’ll keep writing.
On a related note: over the weekend I volunteered as a “Beer Captain” at the Reston (Virginia) Oktoberfest, put on by the Reston Chamber of Commerce, where my wife is the Director of Communications. You may need to get creative, but you should apply this lesson to your social media strategy. Give people fun titles (like “Beer Captain”), ask them to join expert panels, and be sure to publicly acknowledge their accomplishments. If you do this in a thoughtful way, they’ll not only contribute more often, but they’ll push themselves to live up to your standards.