  We have detected occasional, short-lived ``echoes'' of giant pulses from the
Crab pulsar. These echo events remind us of previously reported echoes from
this pulsar, but they differ significantly in detail. Our echo events last at
most only a few days; the echo emission lags the primary emission by only
40-100 musec. The echoes are consistently weaker and broader than the primary
emission, and appear only at the lower of our two simultaneous observing
frequencies. We suggest that these echoes are created by refraction in small
plasma structures -- plasma clouds or magnetic flux ropes -- deep within the
Crab nebula. If this is true, our echoes provide a new probe of small-scale
structures within the inner synchrotron nebula.
