http://www.reddit.com/r/truereddit
http://www.reddit.com/r/indepthstories
http://www.reddit.com/r/askscience
http://www.reddit.com/r/earthporn
also: http://reddit.com/r/bicycling
http://reddit.com/r/linguistics
http://reddit.com/r/beer
http://reddit.com/r/homebrewing
reddit is a fantastic site for communities. The defaults are way too crowded, but the smaller subs are awesome.
http://www.reddit.com/r/truereddit
http://www.reddit.com/r/indepthstories
http://www.reddit.com/r/askscience
http://www.reddit.com/r/earthporn