Hi Flex Bees, we got an interesting API for customizing Maps in our Map based application. This will give more and cool features to our apps.
“MapQuest is committed to providing the best mapping experience in the Flex environment and are continuing to innovate our AS3 and Flex toolkits. MapQuest provides not only mapping, but industry-leading geocoding, routing and spatial search capabilities, all within easy-to-use Flex components that allow for drag and drop creation of your mapping interface.”
Sample screenshot from TourDeFlex
Interesting news is we’ve this API for .NET / JAVA / JavaScript as well. Please checkout the resource page for more details.
Useful Resources,
AS3 Flex – Samples and Tutorials
The MapQuest Platform is available to everyone for free (Free Edition). The Enterprise Edition includes everything available for free, plus account management, live support, service level commitments and enhanced data offerings. If you wish to try the full power of the Enterprise Edition before buying, A Developer License is also freely available and can be accessed here.
Premium Data Sets are also available with MapQuest Platform Enterprise Edition, for both display and search. Datasets in North America include business listings, neighborhoods, parcels, zip codes, counties, demographics, school districts and school points. See more at http://platform.mapquest.com.
Hope this will be useful . 
