We have developed a novel information storage and display structure called EulerView, which can be used for the systematic management of tagged resources. The storage model is a non hierarchical classification structure, based on Euler diagrams, which can be especially useful if overlapping categories are commonplace. Keeping the constraints on the display structure relaxed enables its use as a categorisation structure which provides the user with flexibility and facilitates quick user tagging of multiple resources. As one instance of the application of this theory, in the case when the resources are photos, we have developed the Eulr tool which we have integrated with Flickr. User feedback indicates that the Eulr representation is intuitive and that users would be keen to use Eulr again.