Here some Tutorials and more, what i have found in Splashdamage.
Have Fun 
HUD, Effect, Style
Adding New CVARs
http://splashdamage.com/forums/showthread.php?t=6095
Breath BAR
http://splashdamage.com/forums/showthread.php?t=6310
Bloodsight
http://splashdamage.com/forums/showthread.php?t=9450
Speed-o-Meter
http://splashdamage.com/forums/showthread.php?t=10418
http://splashdamage.com/forums/showthread.php?t=6129
Draw Timer
http://splashdamage.com/forums/showthread.php?t=9395
Covert Ops Pic over Head
http://splashdamage.com/forums/showthread.php?t=6614
Editable Hud Version 2.0
http://www.splashdamage.com/forums/showthread.php?t=12868
Editable Hud Version 1.0
http://www.splashdamage.com/forums/showthread.php?t=10598
Compiling
Compiling a mod under Linux
http://splashdamage.com/forums/showthread.php?t=5886
Compiling a mod under Windows
http://splashdamage.com/forums/showthread.php?t=18357
Fixes
ETPro command map clipping and noncoord fall fix
http://splashdamage.com/forums/showthread.php?t=12320
Shuffle Team: Better Shuffle Algorithm
http://splashdamage.com/forums/showthread.php?t=5880
Some Fixes
http://splashdamage.com/forums/showthread.php?t=9628
forcehunk
http://splashdamage.com/forums/showpost.php?p=147795&postcount=7
Gameplay
Instagib with Sniper
http://splashdamage.com/forums/showthread.php?t=6049
Instagib
http://splashdamage.com/forums/showthread.php?t=6168
Droping Ammo
http://splashdamage.com/forums/showthread.php?t=5935
Player speed in dependence of health
http://splashdamage.com/forums/showthread.php?t=5871
Multi-View Code
http://splashdamage.com/forums/showthread.php?t=13074
http://splashdamage.com/forums/showthread.php?t=7951
Double jump
http://splashdamage.com/forums/showthread.php?t=10119
Class Limitation
http://splashdamage.com/forums/showthread.php?t=10601
Weapons
Smoke Colour
http://splashdamage.com/forums/showthread.php?t=12045
Weapon: Mauser
http://splashdamage.com/forums/showthread.php?t=7081
Adding Weapon with Skill
http://www.splashdamage.com/forums/showthread.php?t=22296
Homing Grenades
http://www.splashdamage.com/forums/showthread.php?t=7368
Throwable Knives
http://www.splashdamage.com/forums/showthread.php?t=8349
Poison Needles
http://www.splashdamage.com/forums/showthread.php?t=8352
UI, Menu
Connect-To-Ip in Server-Browser
http://www.splashdamage.com/forums/showthread.php?t=22146
Favorites IP-Adress
http://splashdamage.com/forums/showthread.php?t=15077
http://www.freewebs.com/xterm1n8or/outpost.htm
Serverstatus ingame
http://splashdamage.com/forums/showthread.php?t=13536
Search Player
http://splashdamage.com/forums/showthread.php?t=12849
Stop Refresh Button
http://splashdamage.com/forums/showthread.php?t=11204
Mod Menu
http://splashdamage.com/forums/showthread.php?t=10169
Mouse Cursor
http://splashdamage.com/forums/showthread.php?t=6933
http://splashdamage.com/forums/showthread.php?t=15287
ÄÖÜ Chars in Chat
http://splashdamage.com/forums/showthread.php?t=20501
Server
Maps CFG
http://splashdamage.com/forums/showthread.php?t=6617
Other
Parsing Files
http://splashdamage.com/forums/showthread.php?t=6943
Other
http://splashdamage.com/forums/showthread.php?t=6716
http://splashdamage.com/forums/showthread.php?t=5980
http://splashdamage.com/forums/showthread.php?t=5969
http://splashdamage.com/forums/showthread.php?t=10918
http://splashdamage.com/forums/showthread.php?t=6240
http://splashdamage.com/forums/showthread.php?t=18356
