Also, don't underestimate the power of the blank screen (B or period for black, W or comma for white in PowerPoint; press again to return to last slide). If you don't have an action item take away to display it can be an effective "I'm done" and bring focus more directly to you for any concluding remarks (including saying a "Thank You"). (It can also be effective in the middle of a presentation to highlight something you want people to hear from you first rather than read.)