For what it's worth, I tend to upvote most "Show HN" threads, because I want to encourage new things. I've never seen a "Thank HN" post before, and thought that

For what it's worth, I tend to upvote most "Show HN" threads, because I want to encourage new things. I've never seen a "Thank HN" post before, and thought that it was worth upvoting because it's nice to see success stories, especially when it's due in large part (according to the OP) on the advice given by this community when the product was in its infancy. I thought that was pretty cool.