I've just made a map of all Stack Exchange sites, except for the three biggest ones:
- The graph is based on users with rep>=200 at a given site.
- Node size is related to number of such users.
- There is an edge between two sites if there are common users more often that one would expect on random, see on observed/expected ratio on Stats.SE.
- Colors are indicating different graph communities (nodes which have much more connections inside a group than with other groups).
Why not include Server Fault, Super User, and most importantly, Stack Overflow?
Stack Overflow, to some extent, is a different story from the other sites. When it comes to Server Fault and Super User - unfortunately, the Stack Exchange API (or at least - my Python wrapper, se-api-py) has some issues with obtaining more than 100k items.
Any questions and comments are welcome.