I recently had to file a change of address with the USPS through their very well designed change-of-address website. I have to say I am impressed with how straightforward the experience was and how the interaction design and information design really sped the user to completion.
Of particular note I most enjoyed the call to actions, which were always a) LARGE and b) explained what would happen next. Well done, USPS. Finally, a web experience by a large faceless agency that doesn't suck!