On a recent show Chris recommended inflation linked bonds to a caller. I have a number of I-Bonds that are currently earning zero percent interest. The earnings rate is determined by a formula that employs both a fixed rate, determined at purchase for the life of the bond, and a variable inflation rate. The inflation rate is now negative. Fortunately the earnings rate does not go negative. Instead it goes to zero. There is also a forfeiture of three months of interest if a bond is redeemed before the end of five years.
See http://www.treasurydirect.gov/indiv/research/indepth/ibonds/res_ibonds_i...