One of the great suggestions we got from colleagues is that the website in its present form assumes that the user is an informed one and hence may not prove to be as useful or engaging for the average citizen. For that reason, we decided to create a discussion page to go along with each pie that allows users to post their arguments supporting the increase or decrease of a particular slice in a pie. Arguments are voted on by others, allowing the best ones to percolate to the top.
Here are a couple of screenshots of the discussion page for the federal budget pie.