SPUF is Steam Powered User Forums, you can chose from many many active sub-forums about any game on Steam, or pop in on the general sub-forums. It’s nerd angst, social hierarchy is based on rep earned from said angst.
Slashdot is pretty cool, although it gives the option to post as ‘anonymous coward’ which allows people post without consequence more or less, sometimes leading to heated discussion. It covers “News for Nerds” ranging from science headlines to gaming ones, with occasional politicking thrown in for good measure. However if you hold any ounce of political belief, it can be funny to share it because there’s a ridiculous amount of tinfoil hat people in there, in addition to ‘government does no good’ bias. That’s counter-weighted by the equal amount of users who aren’t, though.
Which is another thing about /. that makes it ok, the community is balanced in opposites. Equal number of Applefags to Linuxfags who support Winfags to get at Applefags, equal number of Ecofags to Globalwarmingisfakefags, etc.