None of these ideas is unusual, and in fact, at least prepaying principal on your mortgage is usually a terrible idea. Instead, invest the extra cash. If you prepay and suddenly can't pay your monthly payment, you'll lose your house. If you invest the cash instead, you can use that investment to make payments until you're back on your financial feet. And that ignores the tax deduction, the impact of inflation on what you owe, and the higher rate of return you can likely get.