Short-term bond or even CD? As long as you wait until it maturates, you know your money is there, and the interest is yours, too. However, I don't think you can make much interest any way.
There is nothing without risk in the investment world. I would choose fidelity's cash reserve ( cash in fidelity is automatically in cash reserve, any way)since I could use it any time to put into the market. See, it you believe the market is going down for a while, you can take money out every once it drops 5%. :).
