A Stackexchange site might be too. It seems the main difference b/t the two is that the Reddit/HN format is oriented submitting links for discussion and pithy comments, whereas SE is oriented around submitting questions for specific answers and collective problem-solving. The latter might be more what the OP is looking for.
I prefer the subreddit approach, mostly because I subscribe to the subreddit and see new stuff there in addition to all my other reddits, without having to hit an extra site. Mixergy's community (FoundersMix) is great, but I don't care so much for the StackOverflow engine for general discussion.
iirc, they're changing the StackExchange model so that it has to be blessed or approved before you can create one. Additionally, SE isn't really a great platform for fostering discussion as much as it is a platform for Q&A.
