Flex 2.0 comes with a great set of essential components for building RIA’s, but if you have the craving for more top quality components, check out flexlib. It is an excellent open-source component library at Google Code, that contains quite a few components that could be useful in your next Flex RIA.  As you build more and more Rich Internet Applications you might find, like I admittedly did, that having access to more components could in essence expand your palate and consequently the range of things you can do with Flex. This is a terrific, comprehensive repository they have over on Google code so if you are a Flex developer you  have to take a look at.