Cheat Me Once, Cheat Me Twice, Cheat Me Deadly

Here's some great cheat codes for Elder Scrolls IV: Oblivion. Unfortunately, these only work for the PC version.

Console menu functions - While in the game, hit the tilde key [~] at any time to bring up the console. With the console open, there are multiple commands that can be used, some that require targeting by selecting an object with the mouse while the console is open.

Click any human or creature, type "kill" - Instant kills
Click a locked door or chest, type "unlock" - Unlocks target object
Without targeting, type "tgm" - God Mode
tfh - Toggle Full Help
player.additem 0000000F 'XXX' -Adds the desired amount of gold. Replace the 'XXX' with the amount wanted.
modpcs skill 100 - adds 100 points to the skill
modpca luck 100 - adds 100 pointsto an attribute (here luck)
player.setlevel 1 - Changes player level to desired number. Use 1-255
advlevel - forces a level up with the levelup screen.
advskill skill # - Forces a skill level up of # levels, example: advskill blade 4
showclassmenu - Allows you to change your class
Showbirthsignmenu - Allows you to change your birthsign
caqs - Completes all quest stages
psb - Add all spells to player
SexChange - Changes your gender
TAI - Toggle AI
player.setAV <#> - Increase (Or decrease) Ability or Attribute
player.additem - Gives the player the given item and amount of the item.
player.setcrimegold 0 - Removes Bounty on your head. NOTE: If being chased by city guards, you must leave the city and go back for it to work on them.
player.payfine - Guards stop attacking you and bounty is paid off.
help - List console commands
lock [1-100] - Lock selected door or container
showfullquestlog [quest id] - Show all log entries for indicated quest
coc testinghall - Teleports player to an area with all objects, monsters, and NPCs in-game.
stopcombat - Immediately stops the combat of the selected friend/foe.