This is a bit of a sore subject, I've found out a male colleague in exactly the same role is paid a hell of a lot more than myself & a female colleague who are better qualified with more experience.
What really sticks in my throat is I asked for a raise 3 years ago when he was employed as I saw what salary they were recruiting for and outlined what I thought were good reasons to justify a raise. This was declined. Where does sex discrimination start as opposed to being paid more than someone is worth?