And many eyes are better than just one set. Usability bugs are still bugs. Whether the bugs crash the system or confuse the user, they are still product defects. Incorporating that attitude into the QA and engineering department helps incorporate usability into the organization. Usability problems that are found late in the development cycle should go through a similar triage process and get categorized in the bug database in the same way as other product defects.
New employees make good usability test subjects.
They may not be exactly in your target market, but pouncing on new employees is one of the cheapest ways of getting usability data. Make friends with the HR department. They can point new employees to you for testing or perhaps even make testing part of the employee orientation process. Sometimes it's hard or impossible to make all of the above happen in any individual corporate culture. In other companies, getting people to observe usability testing can be like pulling teeth.