this is a job for hashcat.
Also, see the optimized section. I really recommend it: http://hashcat.net/wiki/doku.php?id=toggle_case_attack
Quote:root@thumbstone:~/dev/projects/hashcat/hashcat-0.38# echo pass > word
root@thumbstone:~/dev/projects/hashcat/hashcat-0.38# ./hashcat-cli64.bin --stdout -a 2 word
pass
Pass
pAss
PAss
paSs
PaSs
pASs
PASs
pasS
PasS
pAsS
PAsS
paSS
PaSS
pASS
PASS
Also, see the optimized section. I really recommend it: http://hashcat.net/wiki/doku.php?id=toggle_case_attack