1) Get 32AA batteries from a 6-volt lantern battery:
http://lifehacker.com/software/how-to/get-32-aa-batteries-from-a-single-6-volt-battery-301237.php
2) Get 8 watch batteries from a 12-volt battery:
http://lifehacker.com/software/how-to/get-eight-watch-batteries-from-a-12+volt-battery-291068.php
3) Get 6 AAA batteries from a 9-volt battery:
http://lifehacker.com/software/macgyver/macgyver-tip-use-a-9+volt-battery-as-emergency-aaas-224159.php