280 Slides is a web-based application for creating presentations; a PowerPoint or Keynote for the web, if you will. Built on the Cappuccino web framework, I worked in conjunction with MetaLabs to architect valid and semantically correct XHTML/CSS for the product pages.
Chris Anderson of Ars Technica recently raved about 280Slides. According to him, "280 Slides is a very impressive presentation app that ... runs smoothly and seamlessly. On Mac OS X, it's easy to forget that it's running in a browser and not directly on the desktop."