Here’s a few tools we find useful on projects to help promote
and ensure usability:

Color Challenged Developers?
Here’s a great tool to help your team select color a combination with aesthetic appeal and good usability.
Check out > ColorSchemer Studio 

Need fast, interactive prototypes?
Develop fast interactive prototypes and generate a word doc for the boss and html prototypes for the users. The latest release can simulate AJAX interactions.
Check out > Axure Rapid Prototyper

Spending too much time copying that whiteboard user interface design?
This purpose built software cleans the glare and yellow from the photos you take of your whiteboard meeting notes and outputs an easy to read copy (better than those copy whiteboards!).
Check out > Whiteboard Photo