  Although inflationary models generically predict a flat spectrum of
gravitational waves, we point out a general process that produces a sharply
peaked spectrum of gravitational radiation. This process is generic for
inflationary models with a complex inflaton field which couples to fermions. In
particular, for chaotic models these may be the most extreme gravitational
waves in the Universe with a very large energy density fraction 10^-9 and
ultra-high frequency, 10^10 Hz. Although not amenable to space based
interferometers, the signal from this model may be detectable by future table
top experiments.
