Spillo is the first OS X Pinboard app that is as clean and simple as the Pinboard bookmarking service itself. You can browse all your saved bookmarks in a three-pane window with entries for private, public, starred and unread, plus another section for community-sourced bookmarks. My favorite part is Collections, which lets you make smart collections based on tag, title, URL and more. You can even save a search of public Pinboard bookmarks, making this a great place to keep up-to-date on, well, anything. Spillo costs $10, with a free trial available.