I have a half-finished posting on "A Beginner's Guide to Meme Hunting" with a descripting and list of links. e.g.

Slashdot
Digg
Reddit
Boing Boing

And others. Any big one's I'm missing? (I'm talking specifically about the things that people read largely to say "Oh yeah, I already saw that..." when a coworker comes by to tell you about a "cool site").

B3ta and Fark?

Daypop is usually very good, even though it's been going through a lot of technical snafus lately due to the fact that  the guy who runs it basically runs it out of his apartment...

Metafilter
Kuro5hin

Daypop and that other ones... Blogdex and Popdex track memes more directly than the other sites. I haven't visited them in ages though.

I mostly hit http://del.icio.us/popular

The Onion