The latest version of SMF comes with a new feature that allows users to "Like" a post. I encourage users who don't wish to reply to a post but found it useful or interesting, to click on "Like".
While we'd love everyone to participate with replies, a "like" tells us that others are reading the posts and enjoying them. If it's an entire topic you appreciate, you can just like the first post if you want.
Bill doesn't appear to notice any likes, though I have liked a few of his posts. Has anyone else noticed them? They don't show up in one place, just in the posts you make that were liked.