Anybody can participate in chat by just joining 20 sites?
876
I was able to post in chat with less than 20 rep by joining 20 sites
149335
How to chat to all
49874
He who must not be named? (aka Anyone can ping everyone in chat)
21245
What is the maximum number of people that will join a settlement?
33302
What languages are we allowed to speak in SE chat rooms?
93751
Moving comments to chat: is it just about length?
126526
How do you find out your very first chat in a particular chatroom?
105413
IRC access for the chat?
156793
Why does signing on to one site not sign me on to all of them?
142410
Why does the guestbook chatbox not produce any network activity?
30434
What is the Chat Sandbox, and what do the commands there do?
136670
Why do you need 25 reputation on Meta Stack Exchange to use chat?
111738
Could mods have "add comments to chat" to supplement "move comments to chat"?
107413
"Would you like to automatically move these comments to chat?" could be clearer
10463
How to invite friends to Stack Overflow, Server Fault and Super User?
64550
Link to chat user from profile page
30067
Chat related privileges are not site specific