Financial planners quoted in Readers Digest suggest placing your just-in-case money in a series of short-term CDs that continuously come due. This provides a higher rate of return without tying up a lot of money and gives the option of using it when needed, penalty free.

If you have $10,000 to invest, put $2,500 in a one-year CD in September, then $2,500 in a one-year in December and March. You'll have $2,500 plus interest coming in every three months. You can roll it into new CDs or invest more each time it matures.

To shop for CDs, check with you bank or which lists the best CD rates from banks nationwide. There are no fees when you buy a CD. The penalty for removing money prior to maturity can be up to six months interest.