In recent years, we have witnessed the blooming of Web 2.0 content such as Wikipedia, Flickr and YouTube, etc. How might we benefit from such rich media resources available on the internet? This paper presents a novel concept called Mediapedia, a dynamic multimedia encyclopedia that takes advantage of, and in fact is built from the text and image resources on the Web. The Mediapedia distinguishes itself from the traditional encyclopedia in four main ways. (1) It tries to present users with multimedia contents (e.g., text, image, video) which we believed are more intuitive and informative to users. (2) It is fully automated because it downloads the media contents as well as the corresponding textual descriptions from the Web and assembles them for presentation. (3) It is dynamic as it will use the latest multimedia content to compose the answer. This is not true for the traditional encyclopedia. (4) The design of Mediapedia is flexible and extensible such that we can easily incorporate new kinds of mediums such as video and languages into the framework. The effectiveness of Mediapedia is demonstrated and two potential applications are described in this paper.