Look into this: 12 12 month CDs each maturing 1 month after the next.
Another example of CD laddering:
CD Amount Term Rate APY Maturity
1 $10,000 6.0 mo. 2.71% 2.74% May 17, 07
2 $10,000 12.0 mo. 3.63% 3.69% Nov 17, 07
3 $10,000 18.0 mo. 3.63% 3.69% May 17, 08
4 $10,000 24.0 mo. 3.83% 3.90% Nov 17, 08