Shadow fonts or shadows on shapes seems to be popular these days on PowerPoint slides. Why, I'm not sure. Most of the time I see a shadow used it is used for one of two reasons. First, the presenter added a shadow because they think it looks cool. For those of you have attended my seminars, you know that one of my key philosophies is that "Clear is more important than Cool". Research has shown that any distracting elements on a slide reduces the audience's understanding of your message. So if you are adding shadows to be cool, think of better ways to make your slide visually interesting and clearer. The second reason that presenters add a shadow is because they have selected colors that don't contrast very well and think that a shadow will help their audience see the shape or text. If you have made poor color choices, then pick higher contrasting colors, don't add a shadow to compensate for your poor decisions.