Here’s some from Tumblr:
20yardsoflinen - The title is taken from a passage of Marx’s in Capital. As such, the blog tends to deal a lot with political economy.
pieto - Media ecology, film studies, and critical theory.
foreverybody - International relations and political economy.
modernandmaterialthings - Critical theory, cultural studies, and information technology.
urbanfoodproduction - Urban agriculture, sustainability, and appropriate technology.
ziatroyano - worker’s movements, employment, and labor issues.
dropouthangoutspaceout - political economy, information technology, and video games.
praxismakesperfect - Architecture, art, design, and Marxism.
sociologic - Sociology and social theory.
criticalculture - Cultural studies, gender issues, and class struggle.
Not from tumblr:
Lenin’s Tomb - Marxism, political economy, and workers’ movements.
BLDGBLOG - While not explicitly a politically radical blog, it often proposes radically different ways of thinking about and using the built environment. It’s also incredibly interesting.
(sorry about the delay)