A new service called Poll Everywhere allows you to set up interaction with your audience via Twitter. Your audience can participate in surveys or ask questions via Twitter, and results can be included in real-time in your PowerPoint presentation. Poll Everywhere is free for up to 15 participants, then has a subscription model depending on the number of audience members you require.

Another interesting presentation service that uses Twitter to interact with your audience is Visible Tweets, which is a free web-based service that displays tweets from a specific user, or with a specific tag using stylish Flash transitions… would look very neat on LCD displays around a conference venue.

Visible Tweets using 'Rotation' effect