Interaction design isn't about static states. Terrific resource for creating fluid experiences.
Too often we focus on individual states of an application or website we're designing, when in the end actual use is something much more fluid. It's important to consider the 'inbetweens' as a way to reinforce parts of the experience.
Johannes Tonollo has put together a great resource that outlines a number of key animation and transition techniques that any designer can benefit from.
