Thanks for bringing the problem up. I never contributed too much but dropped in whenever I felt I had something insightful to say. Recently it has been getting less frequent but I think it's just that many of the front page stories aren't as interested as they have been and there is a good amount of duplicates. Since the community is large the comments tend to drop down faster as well so it's more difficult to get a discussion going.
A possible idea is to put up a dump of the HN data somewhere for users to download. Maybe the community can analyze it and find interesting patterns/behaviors and possibly solutions?