PayScale is a website that allows you to compare yourself to other people who have the same job as you according to salary, benefits and other information.

From the website:

PayScale is a market leader in global online compensation data. With the world's largest database of individual employee compensation profiles, PayScale provides an immediate and precise snapshot of the job market. Our patent-pending real-time profiling system indexes custom employee attributes (such as industry-specific certifications) and specific job titles for every industry.
PayScale Professional provides employers with accurate, reliable compensation detail never before available. My PayScale and PayScale Premium give individuals the accurate facts and negotiation know-how they need in order to make smart, informed career decisions.