SAP has created a tool that displays tweets inside PowerPoint, with lots of variations and customization options. It’s a way to interact with the back channel while you’re presenting in a very cool way. For example, you can enter a search term and current tweets using that term will appear on the slide. Or show as a ticker along the bottom. You can even poll the audience by telling them to tweet their choice of options.
You can download it here. (Update: This tool may no longer work. See the comment on the linked page.)