OPML workstation provides a tool for PPT to OPML conversion. You'll find it on the left navigation area under File import. This is an option for hosting slideshows that lets you include slide notes, the slide and the content from the outline view.
Here's one I prepared earlier (sorry Kathryn the slide has the wrong title for your blog). It is just a test, so don't expect any great content.
In the conversion process the user can specify the slide size. Right now if you choose slides wider than about 500px, some of the slide will be hidden due to the layout of the website. The creator's profile occupies a sidebar that interferes with the slide display. In my example I reduce the slide size to <500px so that it can be viewed more easily.
I'm not sure whether/how these slide opmls can be embedded in other web pages. But that would be useful.
There are a number of educational slides hosted on the site. Browse the list, choosing Folio type "presentation".