An idea: feedbackshare.com
feedbackshare.com -- give feedback, get feedback. A fair feedback sharing site for webmasters.
The idea is simple.
1) You create a feedback request which consists of a link, and some guidance as to the feedback you want (there should be guidelines: eg - it shouldn't take more than 10 minutes to provide this feedback). (Note: After the site has a decent sized pool of feedback requests, it's probably a good idea to require that a user has given at least 1 feedback before being allowed to create a feedback request, otherwise people will just "create and wait")
2) You provide feedback to other posts. Your feedback is anonymous (though of course you can provide your identity within, if you want). Feedback is measured by number of words, sentences, or some other intelligent metric. All feedback is hidden.
3) You are notified when someone answers your feedback request. You only get what you give. You must have provided similar feedback (as per the aforementioned metric) to another website in order to view feedback for yours. For example, if you've submitted 3 high quality feedbacks, you can view up to 3 high qualify feedbacks on your post. A "credit" system would work.
I believe a lot of "Show HN" posts go unnoticed because there's really no incentive to answer them. This should eliminate the problem. The process is easy, painless, and instant... go around giving feedback, and in return you can view feedback people have given you. It's win-win.
I've already registered the domain name. But if you make it, I'll happily point the domain to your DNS server, so long as the site is operational, free, and gives me props for the idea. Or, you can find your own domain name and launch it there. I just want to see and use the service :)
Thanks.