Download Root Explorer
Navigate at directory /data/misc/wifi
read wpa_supplicant.conf file!
on some devices is /data/wifi/bcm_supp.conf
original article http://www.addictivetips.com/mobile/how-to-view-passwords-for-wi-fi-access-points-saved-on-your-android-device/
origin - http://www.pipiscrew.com/?p=2179 view-passwords-for-wi-fi-access-points-saved-on-your-android-device