Mockup Tools FTW #DesignGeek

The more I strive to meet customer expectations for excellent web-based applications the more I come to appreciate the value of mock-ups and prototypes.  While we were still dating my now-wife worked as a User Experience engineer for Dell and routinely batted me (a Dell software engineer) over the head with the subject of usability years before "Web 2.0"  and user-experience were en vogue.  She gifted me with Jakob Nielsen books and offered (unasked-for) assistance in critiquing my own applications.  Back then low-fidelity prototypes and early user feedback were still a novel idea.  Now, however, I find them to be nearly-indispensable steps in satisfying customer expectations...