>>uuilly+(OP)
I've always been hopeful that lobste.rs would take off, but sadly the steps they took to ensure good participation has kept it from growing. I mean, it still gets new articles, and there are a very few items that aren't on HN (or showed up sooner), but most posts have very little discussion. Looking at the homepage, and the majority of links have 0 comments.
That said, it's got a few features that people have pitched as the solution for HN (tags being one of them).