forkbomb is tool for stress testing. It can create many processes
using fork(), bring up some zombies, allocate memory using
realloc() and accesses this memory. It has different switches for
fine-tuning operation. While classic fork() bomb is good only for
fun and QA release testing, running multiple memory-eaters can be
useful for determining maximum memory which can be given to
servers (bind or squid) without taking machine down.  You can
test different operation systems with this tool and see how they
are handling the load.

WWW: http://home.tiscali.cz/~cz210552/forkbomb.html