Countries are colored by monthly Wikipedia page views per internet user (2011 Q4). Overlayed on the map are monthly unique visitors per region (Dec 2011).
Country coloring: Wikipedia lists internet users per country & population per country
+ page views per country -> aggregate data
Unique visitors per region: data kindly supplied by internet research company comScore
1) comScore publishes one UV count for Middle East & Africa combined (40 M in map above).
2) In many countries the number of internet users grows rapidly from year to year. Not all data in the Wikipedia lists are quite up to date. This can influence the shown ratio significantly. I hope some day we will have a more up to date data feed from e.g. World Bank, which publishes tons of metric via a very flexible API.
3) Like Stu I used this neat mapping tool http://gunn.co.nz/map/
4) With current coloring it is a bit difficult to see the which countries have 15 views per internet user, which have 25. No large countries rise above 17 views per user. Check for details page views per country.