Have you ever had an idea on how some web or desktop UI should look and needed to tell someone about ? Your text explanations would be misunderstood or you were just too lazy to even write it down or use any of the many useless expensive tool to make it ?
I've been in that situation many times lately while working on JBoss Tools and Developer Studio, but ever since I bumped into Balsamiq Mockups I'm (almost) enjoying doing mockups of UI features which I hated doing before.
Thus instead of me trying to explain how it works go see the screencast here and see it for your self.Note:
I do not have any associations with Balsamiq, I just find their product to be really good and solving a problem I know alot of others have and wanted to share that.