*#*#4636#*#* - phone information,
*#*#36245#*#* - access email debug information
*#06# - IMEI info,
*#*#225#*#* - calendar,
*#*#759#*#* - access Google Partner Setup,
*#*#426#*#* - debug info for Google Play Service,
*#*#8255#*#* - Gtalk Monitor,