Do you want to know how much your coworkers really make? Take a look at Glassdoor. It's a list of salaries and work conditions for specific jobs in specific companies.
Anyone can access the information, provided they first write a review of their own job. You list your job title, salary, then go on to evaluate your bosses and review your working conditions. It's all anonymous.
Glassdoor is in Beta. There are 3000 reviews so far. But with the "Give-to-get" subscription model, I imagine the number of users must be growing fast.