Ask HN: What is market rate salary?

I am a senior developer. I work with Mule, java, web-services, objective-C, javascript, HTML, jQuery, javascript MVC, SQL, blah, blah, blah. Needless to say, I am a generalist who works in many different technologies. The company I work for is trying to learn how to hire good talent. We are based in Arkansas so cost of living is low, but it is also harder to get talent to come here. My main question is around salary. What is market rate salary? Every job listing on here says they pay market rate? I am just wondering what that is, to find out if I am being compensated correctly. Also, at the company I work for, there are no project bonuses or equity allocations. My salary is all that I get. I will appreciate any useful comments or advice.