Agreed. "Show HN" posts are probably the most important part of HN to me. I don't always comment, but I always enjoy seeing them, and I love it when you see somebody post something that is incredibly useful to the OP. It warms the heart to see one of those conversations that goes:
somerandomuser "I like this, but FOO seems kinda wonky. We did something similar once, and found that BAR increased our conversion rate by 12.9%"
submitter "Holy shit, that's a great idea. I never thought of that, but I'm going to implement that tonight! Thanks for sharing."