It's a low-comment sub, but I'm a big fan of /r/damninteresting It's described as "The reddit-specific version of the curated links section of DamnInteresting.

It's a low-comment sub, but I'm a big fan of /r/damninteresting It's described as "The reddit-specific version of the curated links section of DamnInteresting.com. These represent the nifty articles we've found (and occasional written) about science, history, and psychology." I enjoy it because it's a shotgun approach to knowledge, rather than specific domain knowledge.