This paper describes Gallery, which is our under developing experimental system for supporting the management of personal digital knowledge repositories and which enables its users to explore and utilize their own knowledge collections easily and efficiently. This system features directly manipulatable visual representation of knowledge on a zoomable surface and facilitate knowledge recalls by image and text cues. The current prototype system is based on annotated images as knowledge items, and a corpus contains more than ten thousands of digital photos is used for evaluating this prototype system.