Bookmarks
Mathematical Etudes 
MathOverflow
Quanta magazine
reddit/math
Guilds
Association for Mathematical Research
American Mathematical Society
Canadian Mathematical Society
European Mathematical Society
Readings
One hundred reasons to be a scientist (2005) 
Thomas W. Körner - In praise of lectures (2004)
Steven Zucker - Teaching at the university level (1996)
Francis Su - Mathematics for human flourishing (2017)
Daniel J. Woodhouse - An open letter to the mathematical community (2019)
Comics
Best bits from SMBC 
Choice cuts from XKCD 
