FizzBuzz using CL:FORMAT:

(loop for i from 1 to 100
   do (format t "~:[~:[~S~;Buzz~]~;Fizz~:[~;Buzz~]~]~%"
              (zerop (mod i 3))
              (zerop (mod i 5))
              i))

I tried to fit it all into the control string itself, but boy is that scary.