Matilde Marcolli
NoncommutativeGeometry
Arcadian Functor
Ars Mathematica
Joachim Cuntz
Theorema Egregium
Vlorbik on math ed
Secret blogging seminar
The n-Category Cafe
Bill Crawley-Boevey
Michel Van den Bergh
Markus Reineke
The Everything Seminar
Vivatsgasse 7
The unapologetic mathematician
The infinite seminar
Terry Tao’s whats new
Bernhard Keller
Not Even Wrong
The geomblog
Alain Connes
Richard Borcherds
Sage blog