[T-Mobile Samsung Galaxy S 5] Forcystos:
Found a couple of codes. Most of them have already been listed elsewhere, but there's some that might want to be tested out.

197328640

27663368378

2684

0011

123456

32489

2580

232337

232331

232332

9090

73876766

738767633

7387678378

7387677763

4387264636

4238378

1575

6984125

2886

2767*2878

1111

2222

8888

301279

279301

2263

58366

CP_RAMDUMP

37375625

EDIT: Some more codes I found on a forum pertaining to the Ativ S, but could also apply.

- Rebooting *#350#

- MultiTouch *#0987#

- SWversionEx *#1234#

- SWversionNewIn *#9562678**

- SWversionNewIn_COMMON *#16199112*

- buildInfo *#99732#

- ProductionError *#732873#

- LcdTimeoutON *#250#

- LcdTimeoutOFF *#251#

- SMDINFO *#03#

- PVKKey *#99785#

- PVKFileName *#997856#

- SerialNumber *#737425#

- DebugOption *#7450#

- ScreenCapture *#666777#

- CHNLPR *#246577#

- CSCConverter *#78*598031

- CSCConverter_inner *#24320#

- CSCConverter_common **#321647335

- unlockdevice *#608090#

- CPUChipInfo *#2784636#

- TotalCalltime *#22558463#

- FTAMain

- VIEWHISTORYNW **#7547#

- VIEWHISTORYNW *#7547#

- SIMPLE_FUNCTION_TEST *#05#

- SELF_DIAGNOSTIC_MODE *#7353#

- BRIGHTNESS_TEST *#3*#

- SOUNDTEST *#0675#

- AccelerometerSensor *#22235#

- BATTERYMONITOR *#9911#

- CAMERAUPDATE *#34971539#

- CAMERAUPDATESVC *#7412365#

- LIGHTSENSORTEST *#0589#

- BATT_TEST *#2*#

- GPS_TEST *#771280*67

- BATTERYINFO *#0228#

- DEVICETEST *#0842#

- RTC *#0782#

- AUDIOTEST *#0673#

- AUDIOTEST2 *#0289#

- ILLUMINATIONTEST *#0843#

- PHONELOOPBACKTEST *#0283#

- USBPATHCHANGE *#7284#

- BLUETOOTH_MAC_VIEWER *#232337#

- BLUETOOTH_RF_TEST *#232331#

- BLUETOOTH_AUDIO_TEST *#232332#

- BLUETOOTH_SEARCH_TEST *#232333#

- WIFI_MAC_VIEWER *#232338#

- WIFI_TEST *#232339#

- WIFI_FACTORY_TEST *#526#

- NFC *#6328378#

- FMRADIORX *#0368#

- FMRADIORX_COMMON *#3689#

- MICROUSB_TEST *#1793#

- LCDTEST *#0*#

- TouchFirmare *#2663#

- TouchDelta_80 *#80#

- BT_LogDisable *#9902*0#

- BT_LogEnable *#9902*1#

- BT_SSPDEbugModeEnable *#9902*2#

- BT_SSPDEbugModeDisable *#9902*3#

- PowerOffSetting *#7594#

- TouchkeySensitivity *#86824#

- ProximityTest *#7769#

- LCDDimmingTestLoop *#5235667#

- CompassLog *#624564#

- EnableNever *#63837#

- APPSLAUNCHER *#914789#

- NetworkSettingInfo *#9920#

- ConnProflieSetting *#9908#

- RUNAPP *#786227#

- IPSetting *#232340#

- CDMATEST *#455037698

- CDMATEST *#455037898

- DMGCF *#15428#

- CDMA_LTE_NETTYPE *#45503589

- SWversionFTA *#9999#

- HWversionFTA *#8888#

- SWversionFTA *#1111#

- HWversionFTA *#2222#

- DEBUGMODE1 *#0011#

- CIPHERING *#32489#

- INTEGRITY *#2580#

- UARTCHANGER *#9090#

- RRCVERSION *#0599#

- GPSTEST *#1575#

- BANDSELECTION *#2263#

- GCFTESTMODE_ENTER *#4238378#

- ReactivateSellOutSMS *#509733**#

- DisableSellOutSMS *#999001**2

- SellOutSMSProductionMode *#561277575

- SellOutSMS *#1784229*6

- POWERONATTACH *#7298#

- OperatorDebug *#37375625#

- AutoReceive_Enable *#4505**554

- CollectLog *#9900*#

- RetailLog *#9900#

- DEBUGDUMP *#0514#

- RILDUMP *#745#

- LOCK_STATUS_INFO *#7465625#

- EN_LOCK_NW *#303176*91

- EN_LOCK_SUB_NW *#13061*685

- EN_LOCK_SVC *#362077129

- DIS_LOCK_SVC *#446255022

- EN_LOCK_CORP *#362072129

- DIS_LOCK_CORP *#446250022

- VERIFYCOMPARE *#9990#

- IMEI_NUMBER *#06#

- RESET_FACTORY *#951001849

- HIDDEN_TEST *#2106*41*1

- HIDDEN_TEST *#3282#

- HIDDEN_TEST *#3214789#

- HIDDEN_TEST *#7597308**

- HIDDEN_TEST *#70*297080

- HIDDEN_TEST *#7597848**

- SAR *#07#

- CSCConverter_common *#321647335