The exception to this article's premise would be subreddits, like programming. Niche groups like programming.reddit or del.icio.us do feel like they have a higher signal-to-noise ratio. I've gotten some great links from programming.reddit, or here, for example.

Main reddit is where I go when I'm bored and procrastinating.

I am actually surprised at how little traffic del.icio.us gets, all things considered. I made it to #4 on the most popular list a few weeks ago, and it only got me 500 or so visitors. Compare that to Reddit, where being #4 would probably get you 15,000 pageviews.

It would be interesting to see a comparison of traffic received via reddit and del.icio.us. Not just in terms of page views but quality too. How many of the visitors subscribe to RSS, sign up, view other articles or buy something?

As I recall from some other people who have compared such things del.icio.us tends to bring a steady stream of traffic compared to a one day torrent. Or at least that was the case for their sites.