As pointed out from comments these are mostly for Samsung, I have integrated some for HTC below. Like I verbalized this is just a commencement we can build form it. If anyone would relish to engender a Google Doc from this information please feel free I will integrate a link to this post.
Code--------------------------------------Description
*#*#4636#*#* Display information about Phone, Battery and Usage statistics
*#*#7780#*#* Restting your phone to factory state-Only deletes application data and applications
*2767*3855# It's a complete wiping of your mobile also it reinstalls the phones firmware
*#*#34971539#*#* Shows completes information about the camera
*#*#7594#*#* Changing the power button behavior-Enables direct poweroff once the code enabled
*#*#273283*255*663282*#*#* For a quick backup to all your media files
*#*#197328640#*#* Enabling test mode for service activity
*#*#232339#*#* OR *#*#526#*#* Wireless Lan Tests
*#*#232338#*#* Displays Wi-Fi Mac-address
*#*#1472365#*#* For a quick GPS test
*#*#1575#*#* A Different type GPS test
*#*#0283#*#* Packet Loopback test
*#*#0*#*#* LCD display test
*#*#0673#*#* OR *#*#0289#*#* Audio test
*#*#0842#*#* Vibration and Backlight test
*#*#2663#*#* Displays touch-screen version
*#*#2664#*#* Touch-Screen test
*#*#0588#*#* Proximity sensor test
*#*#3264#*#* Ram version
*#*#232331#*#* Bluetooth test
*#*#7262626#*#* Field test
*#*#232337#*# Displays bluetooth device address
*#*#8255#*#* For Google Talk service monitoring
*#*#4986*2650468#*#* PDA, Phone, Hardware, RF Call Date firmware info
*#*#1234#*#* PDA and Phone firmware info
*#*#1111#*#* FTA Software version
*#*#2222#*#* FTA Hardware verion
*#*#44336#*#* Displays Build time and change list number
*#06# Displsys IMEI number
*#*#8351#*#* Enables voice dialing logging mode
*#*#8350#*#* Disables voice dialing logging mode
##778 (+call) Brings up Epst menu
N:B: Note that these codes might not work on all Android smartphones and firmware versions. You can still try these codes to check which ones work on your device. If you have any questions, feel free to shoot them in the comments area below.
