Lovely map! Those not familiar with the Sklaven territories are in for a bit of shock (as I was) when I first encountered a territory that connected to 13 others far away. You may want to make the tool-tip and icon for the Sklaven more prominent.
Other than that, this was a lot of fun. I noticed a couple of missing connections, but can only recall The Blasted Wastes to the Broken Spear Goblins.
ALL HAIL THE UNDER-EMPIRE! ALL HAIL THE LORD OF THE WORLD BELOW!
Seriously though, the way that most other super-bonuses are spread across vast territories makes the interconnected Skaven territories (most of which are 1:1 city bonuses themselves) a palatable prize for a sudden boost in income over terrestrial rivals, setting up a very Skaven-esque long game of building up numbers in choke points and slowly spreading out into the isolated corners of the world. First the tunnels, then the Darklands, then the Greenskins, then bit by bit gnawing away at the heart of the Empire of Man.