Paying for home improvements, credit card debt, emergencies ... if you have equity in your home, you're probably eligible to borrow against it by taking out either a home equity loan or a home equity line of credit (HELOC).
Here's when the move can be smart:
When rates are low, and you want make equity-boosting improvements to your home, borrowing against your equity can be a smart move since you'll be adding value to your home and will able to deduct the interest on the money you borrow to do so.
It also can pay if rates are low, and you have a lot of high-rate credit card debt that you want to pay off, assuming you're only using a small amount of home equity and don't plan to run-up your plastic again.
A HELOC can also augment your emergency fund -- especially if you've paid off most of your first mortgage and are about to retire. With a HELOC, you don't owe any money on it unless you draw against it.
(Here's when it's not a great idea.)