Our good friends at Yahoo have a treasure trove of great AS3 UI components (most of them not found in the CS3 release) in their Developer Network. It's what they call ASTRA or the Actionscript Toolkit for Rich Applications. For AS3, inside CS3, it includes tTee, Menu, Tab Bar, AutoComplete, Charts, AlertManager, Audio Playback and Menu Bar components. There is also ASTRA Flex components is you lean that way. Yahoo provides full documentation and examples for all of the components. This is a great resource for all Flash AS3 developers, especially game developers trying to create that perfect UI experience.