KGS Ranked Game Networks
nodes are players and edges (links) are games 
thickness of edges is proportional to number of games
based on ranked games played in December 2010 (data from the KGS archive)
only giant clusters are shown
1d vs. 1d http://upload.wikimedia.org/wikipedia/commons/4/4b/Ranked2010-12-1d-w2.svg (5.1 MB)
1k vs. 1k http://upload.wikimedia.org/wikipedia/commons/3/34/Ranked2010-12-1k-w2.svg (6.11 MB)
2k vs. 2k http://upload.wikimedia.org/wikipedia/commons/c/c6/Ranked2010-12-2k-w2.svg (6.59 MB)
3k vs. 3k http://upload.wikimedia.org/wikipedia/commons/a/ad/Ranked2010-12-3k-w2.svg (5.91 MB)
4k vs. 4k http://upload.wikimedia.org/wikipedia/commons/3/39/Ranked2010-12-4k-w2.svg (6.35 MB)
: The edges corresponding to just one game have been erased. This removes 85-90% of the edges and reduces the number of connected nodes by a factor of 3. However, the general appearance of the network remains the same.
: Bots have been erased too.