I noticed something cool on del.icio.us the other day. You can subscribe to keywords and get a feed of all the sites people are bookmarking with that term. I subscribed to GTD, and although there are a lot of sites I already knew about, not to mention a bit of porn (is the acronym GTD short for some sexual practice?), I've found some good stuff in there. You can even add the subscription to your feed reader. Just click on the tab that says "subscriptions."