Recently we have published a very simple but useful plugin for WordPress that you can use to show PowerPoint presentations online (presentations hosted on SlideOnline.com). By using SlideOnline.com plugin for WordPress you can easily embed presentations from SlideOnline.com into any blog or website.
You are welcome to send me your feedback as well as wish-to-have features. For example, something I have in mind is to enable a way to publish PDF or PowerPoint presentations directly into WordPress (upload PowerPoint -> covert PowerPoint -> embed PowerPoint).
You can download the plugin from the official WordPress directory here SlideOnline Plugin for WordPress or install it directly from WordPress.