David Slowinski works for Cray computers. He found seven Mersenne primes between 1979 and 1996 by using a version of the Lucas-Lehmer test that he has convinced many Cray labs around the world to run in their spare time (time that would be lost otherwise). He had to delay announcing one of his prime records until he got permission to begin looking for it. Since then, he has joined GIMPS. His search for record primes is "not so organized as you would suppose" (his words), as he does not search systematically.