For years I have publically published the hourly bill rate I am looking for as a contractor.
This is not a negotiating problem, because I am publishing the bill rate I want, not my prior bill rates. I'm confident my rate is in the right ballpark as I've been contracting for quite a while and published both too low and too high rates over the years.
The primary reason I do this is to reduce spam. I don't want to hear from potential employers who are not willing/interested in paying my desired bill rate. It is a waste of my time.
You can publically publish your desired bill rate/salary on Careers by using one of the free form fields available to you.
The hard question for people who take my approach is: how do I know what I'm worth? My answer is trial and error. I also spend time talking to recruiters about what they are seeing for rates (always taking it with a grain of salt). There are "ceilings", but they are not absolute and you can fight through them over time.