When John D. Rockefeller was asked how much money was enough, he replied: "A little bit more." If you're looking to make a little bit more on your investments, here are places to find extra cash. Unfortunately, rates are very low and the emphasis has to be on "little" rather than "more."

Please note: none of these stocks or funds are recommended as buys. They may, however, be a good place to start research.

"You're probably having a tough time these days if you live off the interest from your investment portfolio; money market accounts are now yielding a paltry 0.76%," observes fund specialist Ron Rowland.

The contributing editor to Money and Markets explains, "There is no big mystery why this is happening ... Ever since the banking system started blowing up back in 2008, Ben Bernanke and his Federal Reserve have kept short-term interest rates at historic lows. That's great for bankers, terrible for savers.

"Many investors are watching their income slide. These low rates have income-investors looking for new sources of steady interest and dividends. The alternatives are few. And I'm concerned that some people are so desperate that they're risking their principal in ways they don't even realize!

"I'm always looking for market leadership; right now, biotechnology stocks are moving up faster than most anything else," says Ron Rowland. In Money & Markets, he eyes biotech ETFs.

"Biotechnology is a fascinating sector, one that's made (and lost) a lot of money for millions of investors in recent decades. That's why, in my opinion, you should become familiar with this industry.

"Broadly speaking, it's the application of technology to biological materials - plants, animals and people.

"Nowadays a lot of biotechnology involves manipulating genetic material: The DNA that forms the basis for life. The goal is to produce new and useful substances that make life better and, of course, turn a profit along the way.

"The worst crisis of all time, in my view, is the critical global shortage of fresh water," says " Larry Edelson. In Money & Markets, the resource expert offers four water sector plays.

"The world's water crisis is now getting worse by the day. And the global financial and credit crisis is merely one reason why. Another is the ongoing modernization of major parts of the world, which is increasing demand for water, while at the same time polluting it.

"Yet another is major droughts around the world, including in our own back yard, where 60% of the U.S. is officially experiencing a drought.

"New technologies and techniques for better water supply management and improved conservation on the demand side could potentially avert a worldwide disaster. And as a long-term investment, water is one of my favorites. For both its tremendous social cause as well as its profit potential.

The question comes to mind when looking at the latest data on fund flows and yields. That's because people are piling into money market funds -- as a result of the excess of demand over supply, the yields on short-term money market instruments are tumbling. The average yield on a Treasury retail fund was 0.34% at the end of November, compared with 2.9% in December 2007.

Why is this trouble? With some short-term Treasury Bond yields at negative 0.14%, it will be virtually impossible for money market funds to reinvest the proceeds of their securities and new money -- $550 billion poured into money market funds in November -- at anything much above 0%. This means that money market funds will probably need to decide whether they are willing to lose money to keep their investors from losing theirs.

In other words, given the costs of operating a money market fund, there is no way to give investors a positive yield on the money market investment unless the fund manager is willing to forgo their profit. What to do? Consider looking for Certificates of Deposit that are FDIC insured. Although these require you to put away money for a period of months, they could be a better place to secure some of your funds.

Peter Cohan is president of Peter S. Cohan & Associates. He also teaches management at Babson College and edits The Cohan Letter.

As the Dow fell Monday a record 778 points, or 7% -- a third as much as it fell in percentage terms in October 1987 -- the real action was in the money markets. That's because banks are not lending to each other any more and they are not lending to companies or people either. The only reason any credit is flowing is because central banks are pumping money into the system. For instance, the Fed added $630 billion yesterday to global money markets.

Cash is hard to come by. There are two measures that citizens can use to assess how well the money markets are working. Those are the TED spread, which measures the difference between three-month (London Interbank Offered Rate) Libor and the three-month Treasury rate, and the Libor-Overnight indexed swap (OIS) spread. The TED spread is near a record 3.38% (it was 1.1% a month ago). And the Libor-OIS spread is a record 2.46% (it was 0.08% a year ago).

What does this record level of distrust mean? It certainly reflects a loss of confidence in our leaders and our institutions. For banks it means they must either raise capital, merge with a stronger player, or shut down. For companies, it means hoarding cash and trying to get longer-term loans. And for consumers, it means cutting back on expenses and giving up on borrowing more money to cover the remaining ones.

Peter Cohan is President of Peter S. Cohan & Associates. He also teaches management at Babson College and edits The Cohan Letter.

The stocks we cover here at Blogging Stocks have had a lousy run since the beginning of May when we opened for business. Money market funds might be a better buy.

During a period of poor overall market performance -- for example, the S&P 500 fell 4% -- our stocks: Apple Computer, Inc. (Nasdaq: AAPL), eBay, Inc. (Nasdaq: EBAY), General Electric (NYSE: GE), Google Inc. (Nasdaq: GOOG), Microsoft Corporation (Nasdaq: MSFT), Time Warner Inc. (NYSE: TWX), Wal-Mart Stores, Inc. (NYSE: WMT), and Yahoo! Inc. (Nasdaq:YHOO) -- have fallen an average of 6%.

With short-term interest rates rising, it seems clear that money market funds -- which yield almost 5% -- are a better bet than the average stock.