Codes
Cheat dialog

After applying "CheatCode = chipotle" in configuration-file, open console with ~ and use command "game.toggledebugmode".

With debugmode turned on you can press SHIFT+T to open CheatDialog to alter Gold and Technology
Code .................................... Effect
SHIFT+T ................................. CheatDialog

Debug Codes

Open the "civ4config" file found in your Sid Meire's Civilization IV install directory (Default is "C:\Documents and Settings\Owner\Application Data\Firaxis Games\Sid Meier's Civilization 4") find "cheatmode = 0", change it to "cheatmode = chipotle". During any game, open the console by pressing the tilda key "~", and type in one of the following then pressing enter.
Code .................................... Effect
Console.Clear ........................... Clear the console
App.crash ............................... Crashes game
Game.showWBPalette bool bCreate ......... Debugging
help .................................... Displays all console codes
Console.History ......................... Dump console command history
Game.AIPlay <turn #> .................... Forces AI to plat a certain number of turns
Profile.morphGlobe <integer> ............ Morph the globeview count times.
Profile.rebuildCity <x coordinate>, <y coordinate>, <integer> Rebuild city indicated number of times
Profile.rebuildPlot <x coordinate>, <y coordinate>, <integer> Rebuild plot indicated number of times
Graphics.ReBuildTerrain ................. Rebuilds terrain and lighting
Xml.reloadArtDefines .................... Reload Civ4ArtDefines.xml
Xml.reloadLandscapeInfo ................. Reload Civ4TerrainSettings.xml
Xml.reloadGameText ...................... Reload Game Text xml files
Sound.reload ............................ Reloads audio scripts
Graphics.SetHillScale <number> .......... Sets hills' scale
Graphics.SetPeakScale <number> .......... Sets peaks' scale
Player.setGold <player #>, <amount> ..... Sets players gold (0 is active player)
Sound.noMusic ........................... Stops music
Sound.stopSoundScape .................... Stops soundscapes from playing
Game.toggleTextureAccessInfo ............ Toggle output of texture loads/accesses to debug output
Console.CreateDocumentation <filename> .. Writes HTML documentation for the current console commands

Insert Unit/City

After active the cheat mode, press ctrl+shift+left click on a tile. A menu will pop up and allow you to insert unit or city for players/opponent.
Code .................................... Effect
ctrl+shift+left click ................... Insert Unit/City

More hot keys

First enable Debug Mode then have either a unit or a city selected and push the following keys:
Code .................................... Effect
(City) Shift +"+" ....................... Add 1 to city population
(City) Ctrl + "+" ....................... Add 10 to city culture
Highlight a city. [Ctrl] + [Alt] + Left Mouse Button City editor
Shift + [ ............................... Decrease highlighted unit's strength by 0.2
Ctrl + D ................................ Display debug menu
(City) "+" .............................. Immediately complete whatever the city is producing
Ctrl + 4 ................................ Increase gold by 1000
Ctrl + Plus ............................. Increase highlighted city's culture by 10
Shift + Plus ............................ Increase highlighted city's population by 1
Shift + ] ............................... Increase highlighted unit's strength by 0.2
Ctrl + Shift + Left Mouse Button ........ Insert unit/city
Plus .................................... Instant production completion for highlighted city
Ctrl + Plus ............................. Level up highlighted unit
Shift + T ............................... Pops up a dialogue to change a certain nations gold and change the era
(Unit) Ctrl + "+" ....................... Unit level up
Ctrl + W ................................ World editor

Glitches
Carrying out multiple tasks

You can order your great persons to carry out multiple tasks the same way you can order your workers by holding [Shift]. For example, you can order your great scientist to join the city as a specialist ten times, get some techs, and finally build an academy -- all that with only one scientist.

Secrets
Debug menus and hot keys

After you have enabled debug mode there are a number of hot keys to bring up new menus and edit things on the map.

CTRL + w: brings up the world editor.
SHIFT + [: decreases a units strength that your mouse is over by 0.2.
SHIFT + ]: increases a units strength that your mouse is over by 0.2.
CTRL + 4: increases your gold by 1000.
CTRL + d: brings up the debug menu.

Enable cheats

In your Civilization config-file (check where you installed it), change

; Move along
CheatCode = 0

to

; Move along
CheatCode = chipotle