Power-law distributions emerge when new nodes attach to the existing network with some preference for the current winners. You can increase the severity of the distribution by increasing the preferential attachment, and you can temper it by decreasing it.
For example to increase the severity the trick is to encourage the new comers in the belief that current leaders are a good proxy for their quality measures – it’s a simple message: ‘Go with the winner!’ To decrease the severity you need to provide to new commers with a more complex message: “Pick what’s best for you, here’s a bucket of information to help you do just that.”
Improving the information available to newly arriving members of the network, providing them with more complex subjective information, enables them to make their decision more rationally. That will make for a more diverse network and a less severe power-law distribution.
A system like Epinions.com manages this by creating a bit of a feed back loop that allows existing members to report to new members what they now know. Word of mouth can also help, since a new comer