When your job (or schoolwork) involves giving presentations to rooms full of more-or-less interested parties, you know how hard it can be to maintain a constructive level of audience attention. The economical cloud audience response system (ARS) provided by the mad scientists at PollEverywhere is a great way to spice up a session with quick, engaging multiple choice and full-text questions.
PollEverywhere's polls display wonderfully on the web (if you've got the Flash player) and do well in Windows versions of PowerPoint, where the appropriate ActiveX control to embed the remote Flash animation is available. For Mac presentation apps, however, the path is not so smooth.