This is pretty mild compared to a lot of the other things here but my company (big 3 wireless telecom, so not some small operation) constantly pushes us to do volunteer work outside of working hours / unpaid. It's technically not required, but it's tied to our pay / annual bonus along with our normal performance metrics. So it's not “required” but I get indirectly docked pay for not doing it. I'm certain it's 100% legal but that doesn't make it better.
It absolutely sends me up a wall and down the other when my work keeps pushing it, month after month, quarter after quarter. Worse, I know that it's not my company being altruistic but so that they can report “our employees give back to community with X amount of local volunteer work.” They don't verify anything you did either so I can just lie and say I did volunteer work, so it proves that it's not morally driven but a mix of PR and tax write-offs.
As I said, small fries compared to other real problems and I can just lie and not lose money, still annoying though.