also: http://reddit.com/r/bicycling
http://reddit.com/r/linguistics
http://reddit.com/r/homebrewing
reddit is a fantastic site for communities. The defaults are way too crowded, but the smaller subs are awesome.
Coincidentally, I'm seeing myself frequenting HN more often to read actual content, instead of sifting through tons of memes and pictures. HN is also starting to display content faster, which doesn't really mean anything unless you like shouting 'First' in comment pages (even more so now that I'm working, so by the time I visit both sites, the stories are posted).
The community of reddit is nice, doubly appealing when you are having fellow celebrities among your members; however, with the influx of people, it becomes difficult to feel like you are actually contributing.