While at Saavn, we hacked something together for a new social initiative Firefox was heading up. As one of their new social partners, we quickly designed and implemented a sidebar for our listeners.
We wanted a quick and easy way for our users to access trending music and music recommended just for them. This provided a perfect opportunity to test some hypotheses before throwing a large number of resources into experimenting with our main application.
Below are the iterations I went through, in order. We iterated and launched this in a week.