Oxbridge offers iTunes lectures in a bid to make it more accessible to people across the world

This visualization below allows you to see the impact that each user has on the current conversation. The top row contains the group of users who have had the most impact, the 2nd row the group of users who have had the 2nd most impact (et cetera). Users with similar impact are grouped together, and the average score of the group is shown to the left of the group. The author of the article is also shown on the left, in their corresponding group. Each user's score is based on the number of comments the user has made plus the number of votes their comments have received. The scores are calculated relative one another, so while their absolute value is not particularly important, their relative difference does indicate a larger difference in impact on the conversation.