In order to create a tax liability you generally have to create some taxable INCOME. :)
Traditional to Roth conversion is the only one that comes to mind for me. I did that a few years ago when I had very little income and we had to replace our HVAC units. We got an energy tax credit which we were not going to be able to use, so I converted some traditional to Roth, used the tax credit and paid no taxes, so essentially got a free Roth conversion.