I've been playing with a try-online version of Balsamiq and created this mockup in just a couple of minutes. Showcased at Gold Coast Barcamp by Steve Dalton, blogged by Michael Rees, Balsamiq is software for making mockups for websites and software development. Elements can easily be moved around on the page and the hand-drawn look is deliberate to keep the focus on functionality rather than graphic design.
The mockup can be exported to a .png file. A desktop version is available, but this can also be integrated into wikis.