We submitted two entries for the Flex Developer Derby, which, for some reason, are not yet posted at Adobe Labs.
Home Locator is a complete revamp of our Real Estate sample application. We changed the functionality and included a Yahoo! Map that shows the property location. We actually didn't use much of the old code and we focused much more on the usability and look and feel of the application. We spent an incredible amount of time during the design, not even doing actual code. Most of the hurdles we encountered were due to Yahoo! maps not wanting to behave and bugs in the Flex framework, specially when we wanted to skin the application, going away from the default halo (or whatever is called now) look. At the end, we are happy with the outcome. Before you ask, no, we are not planning to give the source away, at least not for now. We are, however, going to post the source for the original Real Estate application for the Beta 3 release.
We have no hopes of winning anything with the other application, My to-do list, since it does not compare to the other entries. It is really a very simple application, and it was developed as part of an article for the ColdFusion Developer Journal. So you can expect to see a step-by-step tutorial based on it and the complete source for download soon.