Usability should be the ulitmate goal of any designer in any project.
Usability testing is the process of observing users interacting with a particular object or system with a view to finding the points of failure and reducing or removing them. If a system has "good usability" then it can be considered to be easy to use from the first interaction. Poor usability results in failure to complete desired goals, and thus a poor return on investment (ROI).
2am Webworks has extensive experience in usability testing and consulting and has worked with partners such as Australian Red Cross Blood Service and Mummy's Wish for the Paint The Town Red campaign, Club Casual Games, and JWT for the Melbourne Writers Festival.