Yeah, I've tried several times to get some feedback from the HN community (most recently for flatnik.com, if you're interested I'd love to hear what you think!).

Simply posting with the "Show HN: " prefix puts you on a couple of twitter feeds/meta-sites. Reddit is normally a better option, because you can post to the niche subreddits and get a bit of interest, even if you don't hit the front page of the whole site (good luck with that, if it's not an image).