1) recently, I had very good success with a professional social networking site in this matter. Recruiter asked what my current salary details are. I told me, "If I give you this information, what information will you give me". Initially he asked me to look in glassdoor but when I said he can also do the same thing, he relented and disclosed that salary for senior software engineer is minimum of $150k going to a maximum of $190k. I was happy with that information.

Also, I discovered recently that companies cannot talk to one another about salaries, but they can all participate in a "survey" where the surveyor aggregates all this information, in a very detailed way. So, every company knows exactly what the other company is paying, even in a different industry. I guess that is another way of fixing price.