I scan 46 Web sites every morning, clustered in bookmark groups I refer to as "Science", "WritingArts", CultPol" and "Ego". I also go through my Google News main page, from which I exclude sports and minimize regional coverage in favor of top stories, international news, and science news. Curious headlines, interesting stories, or anything that falls within a specific range of my interests generally get posted into Link Salad.
As the day goes by, I have a bookmark group called "Reloads" which I check every few hours that I happen to be near a keyboard, time permitting. That's weighted towards politics, where the breaking stories I'm most interested in, tend to happen, but it also picks up some writer and automotive blogs.
People also send me links on a fairly regular basis. I don't always use them, for any number of reasons, but often as not I do.
When assembling Link Salad, I put them together in a loose order. The political stories, including my ranty comments, appear at the bottom. This is so people skimming for writing or science or other news don't have to read them if they don't want to. (Not everyone shares my political views, obviously.) Personal news about writing, awards and cancer go at the top. Everything else spreads in between, usually but not always science, then culture, with miscellaneous stuff inserted where it makes a sort of thematic sense.
I never, ever use stories from FOX News or its affiliates. Anything with the FOX brand. I'm not averse to conservative sources, but FOX's long record of knowing distortion of the truth is extremely well-documented, as is the singularly ill-informed nature of their viewership. I simply assume anything on "fair and balanced" FOX is wingnut propaganda. (I have been known to see a FOX headline and invest some effort in finding the same story from a reliable source.) I very rarely cite The Wall Street Journal for much the same reason. Unlike FOX's nonstop drivel, their reporting actually can be excellent, but their editorial page and policies are the country club version of FOX's trailer park wingnuttia, which renders even good reporting useless. WSJ is FOX's paranoid bigotry and counterfactual fantasies in a nicer suit, basically.
Beyond that, stuff I note or that falls out of the sky on me winds up in Link Salad. If you see something interesting, tip me. I'll credit and link to the first person who sends me something.