Pecha Kucha is a presentation format in which each presentor must use 20 slides and they must talk about each slide for 20 seconds. This enforces a time limit upon each presentation of 6 minutes 40 seconds. It was devised by Astrid Klein and Mark Dytham. You can read more about it on the Offical Pecha Kucha Site or on the Wikipedia Pecha Kucha Page.