How does one Stack Exchange site know that I'm logged in to the other?
38383
Global auth is dead! Long live universal login
126320
How to find from what computer I connected to a current server
7383
How are new Stack Exchange sites opened?
151022
Signing out of Stack Exchange does not sign me out of my email provider
79129
How to link back to the original site the user came from after he jumped to a subdomain with a "different" product?
83268
Is your MAC address revealed when you hit up a website?
91457
How can I see flags I cast from all sites?
17481
How to log out of a Stack Exchange site?
42044
How does reputation between the main site and its meta work on SE 2.0?
56900
How do users get started on new Stack Exchange sites?
36912
How can I verify users the first time they log in?
45985
How to see Login history?
130824
How to determine the date a Stack Exchange site graduated from Area 51?
157661
How to get data (question details) of a specific Stack Exchange site?
58686
Logging out of Stack Overflow or any Stack Exchange site?
67843
Determine logged-in status of users
84581
How to login in two accounts in the same browser?