The Web site Slideshare.net contains a large number of PowerPoint presentations uploaded by various people. Registered users (registration is free) can download some of these. There are quite a few interesting presentations that could be useful in a faith formation context.
The one below, for example, one could easily be used in a lesson on prayer or simply as a prayerful meditation:
Prayer of Adoration
The following is a presentation created for the Diocese of Peoria Summer Institute outlining the development of the Church's Social Doctrines: