Standard Tree Flex component is useful when in need to display hierarchical data as an expandable tree. Josh Tynjala has developed more advanced component with similar functionality, TreeMap Flex component. Currently in version 2.0 beta, which means bugs are unavoidable. This component is published as open source. More info and code on google code pages .
TreeMap uses 2D canvas to display relevant data rather then simple hierarchical list in Tree component. Component has advanced data descriptors and custom node and branch renderers. This opens new space for new functionality ideas. Excellent work.