Advogato.org is a website in the style of slashdot, but with a vastly different karma system. The comments tend to be more restrained and better thought out than /., and there are far fewer comments per story or writeup.
Designed as a research test bed, advogato uses a trust metric instead of karma to rate its members. Depending on how your peers rate you, your comments will have a different colour header; representing your status of Observer, Apprentice, Journeyer or Master.
Apart from news-style articles, advogato.org also contains good quality editorials and weblog diary entries.