Recipes
Scott Johnson points out that, when you put recipes in your weblog, it's good to put each recipe on its own page. This helps search engines: a common search strategy is to look for (say) "spicy noodle recipe", and this is going to fall apart if you talk about "spicy pictures", "bland noodles", and "software recipes" on the same page.
This is an interesting point, because it suggests an emergent application. Nobody planned to construct a Web-wide recipe service, and nobody planned to participate in one. It simply happened.