One user answers all questions or tag monopoly
21437
The Complete Rate-Limiting Guide
14309
Collapse comments on old questions
37629
Combinatorial card game
139005
(Nicer) user leagues per tag
15852
Posting and answering questions you have already found the answer to
121370
Easy way to access all of my asked questions
3666
Show OPs if someone is answering, live
68040
How can I read all answers on Quora without having to register?
122211
Long answers on stackoverflow
127692
One comment per user per post but be able to reply to existing comments
14062
May I summarize all answers
80592
Sharing reputation for good comments that contribute to the quality of the answer
118095
Let any site onebox with  tags
77934
Why there isn't a feature that lets any user on SO to request other user to answer their question?
156792
Comprehensive question quality blocks now enabled everywhere
109377
Main tag of a question
94817
Allow me to save an answer