I haven't made an hourly salary in 12 years (when I first started working as an engineering assistant). People can complain about unpaid overtime all they want, but I feel if your working hard, most employers give ample (project time). If your work isn't getting done, either you didn't think the design through, or your slacking off. Now there are some cases (and I have worked at such a place) where there is never an end of work, and no matter how hard or how long you work, there is always more work, and it is always unpaid.. I think if your unhappy, then your just not working at the right place. I work for a place that has been family owned for over 40 years, and they never "expect" overtime, people volunteer to put in a couple hours a week if need be to get a project finished, but your allowed slack later on when things slow down. I'm also paid pretty well for what I do, and I'm also learning a lot (on-the-job) so I certainly can't complain.
I guess what I'm saying is that if you enjoy what you do, get paid well, then overtime is not really slavery, or free work, it's volunteering to want to finish a job your enjoying.