I decided was that if I was going to take the time to read something, I would get something out of it. I would only read things that were genuinely useful, interesting, or valuable in some way. I had to come up with a way to force myself to think about what I was reading a little, so I kept a text file on my desktop with a record of every single article I had read. I started with just copying the URL and writing a 1-3 sentence summary, and even this was enough to make me think twice before opening links - "Is this article worth the effort to think about it enough to write a summary?" That was still pretty quick, so I added two more requirements- a 1-3 sentence critique of the article- just what I thought about it, whether I thought the author was incorrect/lying/exaggerating, etc. - and something interesting in the article- the kind of thing I might bring up if I was telling somebody about it.
Writing these things for every article started to feel a little like English class, but it worked. I got in the habit of pausing to think about whether I should click a link or continue reading, I started reading closely and critically, rather than just skimming half of it and moving on, I started paying attention to which news sites, blogs, and domains had worthwhile content and which had garbage, and most importantly, I would actually remember what I had read, and could talk or think intelligibly about it. Also, even though I was only 'requiring' myself to write a few sentences about each article, I found that I often didn't mind writing more, and trying to put some simple structure into my written thoughts would lead to new insights.
I've stopped regularly keeping the journal, but the habit of thinking about what I'm doing while surfing sites like HN has stayed with me.
I think some people probably do this naturally but I've found that I tend toward zombie-mode.
I've recently taken to discarding my bookmarks and relying on other methods to save interesting links. If I want to save something for later use, I'll tweet about it, write a tiny blog post about it, or jot it down in a notebook. I'm not terribly diligent about it, but it's made a huge impact towards helping me filter what is truly important.