For The Flex Challenge, I decided to try and build something like PictureStories, which takes a simple sentence and allows the user to turn it into a rebus. I decided to spice things up by making the source sentences be the titles of posts in RSS feeds, and having the images come from the results of a Yahoo image search.
You can view the resulting application here, and view the mxml and AS source here. Note that due to Flash's security restrictions, the only feed that we can use is the "Digg [local]" feed, which is using a locally-saved RSS feed.
It was an interesting experiment to try and simultaneously explain Flex/Flex Builder, and build an application, and eat cookies, all in under an hour. Flex is a great system for quickly creating simple (or complex!) applications!