CloudMade Tile Request Graphics
I just found a neat feature from CloudMade, a heat map showing intensity of their tile requests at each zoom scale. As can be expected, Europe and North America are the definite zones of high activity. It's also interesting to note the high activity in other regions such as Chile and the Philippines.
[caption id="attachment_272" align="alignnone" width="300" caption="Above: CloudMade's Tile Request Graphic"][/caption]