Check out this heatmap of Tiles@Home data. It shows the size, and thus an approximate complexity, of T@H tiles uploaded to the server. A blank tile of the middle of the sea is much smaller than tiles with complex map data on them. Click for the original image an read more here
Pingback: Living with Dragons » Around the OSM Blogsphere
Pingback: igorbrejc.net » Fresh Catch For June 9th