A friend was told to freeze her ovaries or ovarian tissue before her chemotherapy (for breast cancer), is this a common practice or still experimental?

Common practice: Yes this is common for women of child bearing age who wish to have children in the future, because chemotherapy can affect the ovaries and make a woman infertile.

Great option: This is a great option for women interested in having children. Your oncologist should send you to a infertility specialist who can work with your oncology team. Care can be coordinated so that treatment can begin while eggs are harvested.