This was a funny one.  I was working in support for a completely different project for the Department of Defense.  I happened to be sititng accross form a project manager on another project who was having trouble with getting a design approved for a new project that dealt with helping service members returning from deployment with brain injuries.

I offered to jump in and help, and after getting the basics of the project, I created the above mockup in about an hour.  Considering the audience I was designing toward, I wanted to keep the pages as simple as possible.  I tried to keep all of the functionality./architecture clearly broken out, and make each page only do one thing (to make it as easy to use and comprehend as possible).

After getting preliminary approval for the low-fi design above, I created a full prototype for the site which looks like this:

As an interesting footnote, these designs survived several approval cycles and ended up being used as the design for the website.  Personally, I was really pleased not only to be able to help out a really important project, but to also “un-stick” a project that had been frozen for weeks with just a few hours of work.