Savers constantly fight the threat of lower interest rates. While borrowers rejoice at the prospect of lower costs for credit, savers have to reconcile themselves to either earning less interest or taking more risk to maintain their income level.

Traditionally, conservative savers have looked to banks to hold their savings. They take comfort in the FDIC insurance that protects their nest eggs. No matter how an FDIC-insured bank uses their deposits, customers will get up to $100,000 of their money back -- even if the bank goes belly-up.

Going beyond the bank
Now, however, banks aren't the only game in town. Some non-bank companies are offering accounts that act exactly like bank savings accounts. Compared to some banks, they offer extremely competitive rates.

For instance, Ford's (NYSE:F) Interest Advantage program accepts investments as small as $1,000, paying interest rates that are well above those offered by banks. Depending on how much you invest, compound yields range from 5.39% to 5.70%.

Similarly, GMAC Financial, a division of General Motors (NYSE:GM), offers demand notes to investors. Currently, it pays 6% interest. In contrast, short-term Treasury bills currently pay less than 4%, and your local bank might pay even less on a savings account. Even bank CD rates are falling in response to the Federal Reserve's latest cut in the federal funds rate.

Going uninsured
The big difference between these programs and keeping your savings in banks is that your money isn't insured by the FDIC. Essentially, if you open an account with Ford or GM, you're making a direct investment in the company that puts you among the ranks of corporate bondholders and other creditors in those companies. And with both companies rated below investment grade, there's a real risk that you'll lose every penny if something happens to them that leaves them unable to pay their debts.

Of course, the higher rates are intended to compensate you for that default risk. For the moment, however, that extra interest doesn't amount to much. For example, the bank division of Countrywide Financial (NYSE:CFC) is paying 5.5% on its insured online savings account. No matter what you think of Countrywide's prospects in its mortgage business, the FDIC backs up $100,000 of your savings with its bank.

So is it worth it to risk your entire account balance to squeeze out an extra fraction of a percent in interest? Unless you can be absolutely certain that Ford or GM will make good on their debts, the answer is no. And even if you're willing to take on that risk, you deserve more than what either company is paying you in return.

You can learn more about saving by reading about:

Get the scoop on making the most of your cash in our Savings Center.

Don't let falling savings rates threaten your lifestyle. Make your money go further with advice from our personal finance newsletter, Motley Fool Green Light. Every month, you'll find tips that add up to $450 or more of savings for you. Try it out for 30 days with no obligation and see how Green Light can save you money.

Fool contributor Dan Caplinger sticks with insured bank accounts for his savings. He doesn't own shares of the companies mentioned in this article. The Fool's disclosure policy is a saver's dream.