1. Enabling the CLUA Console

C:\User\My Documents\Baldur's Gate - Enhanced Edition
Open up the Baldur.ini with a text editor. I suggest ConTEXT as its free and will also enable you to easily edit scripts too.

Add these lines 'Program Options', 'Debug Mode', '1', You can put it right at the top if you like

   
CREATE TABLE options (
	section string,
	name string,
	value string
);
INSERT INTO options ROWS (
	'Program Options',	'Debug Mode',	'1',

Start up your game and either create a new game or load a save. Hit Ctrl+Space
This will bring up a window where you need to type in the following:
CLUAConsole:

Useful Console Commands

CLUAConsole:ExploreArea() Set current area to fully explored

CLUAConsole:SetCurrentXP("[Number]") Set XP for selected characters
Example - CLUAConsole:SetCurrentXP("1000") will SET the current character at 1000 experience points.

CLUAConsole:AddGold("[Number]") Sets the party gold
Example - CLUAConsole:AddGold("1000") will give the party 1000 gold.

CLUAConsole:CreateItem("[Item name]") Creates an item in the leaders inventory
Example - CLUAConsole:CreateItem("SW1H01") will create a long sword.

CLUAConsole:CreateItem("[item]", [number]) sets the amount of charges that an item will have upon spawning it- if the item has charges anyway.
Example -
CLUAConsole:CreateItem("POTN08", 10) will create 10 potions of cure light wounds.
CLUAConsole:CreateItem("amul17", 50) to get a Greenstone Amulet with 50 charges
CLUAConsole:CreateItem("scrl75",99) 99 Identify Scrolls

CLUAConsole:CreateCreature("[CRE FILE]") Spawn a creature
Example - CLUAConsole:CreateCreature("GIBBER") will create a gibberling using GIBBER.CRE

Example:
CLUAConsole:MoveToArea("[Area Name]") Move selected characters to an area
Example - CLUAConsole:MoveToArea("AR2300") will move the player to the Friendly Arms Inn.
From @CamDawg - A list of area codes is available as part of the IESDP; use the original BG area codes.

CLUAConsole:WriteScript("[Directory Name]") Output scripts to directory
Note: If the mouse is over a creature, the command will evaluate the scripts attached to that creature. Otherwise it will evaluate the area scripts.
Example - CLUAConsole:WriteScript("DebugScripts") will output the script results to a folder called DebugScripts in the root of your BG install.

CLUAConsole:SetGlobal("CHAPTER", "GLOBAL", [Chapter Number]) : Advance to Chapter X
Example - CLUAConsole:SetGlobal("CHAPTER", "GLOBAL", 2) Would advance to Chapter 2

CLUAConsole:GetGlobal("CHAPTER", "GLOBAL", [Chapter Number]) : Advance to Chapter X
Example - CLUAConsole:GetGlobal("CHAPTER", "GLOBAL", 2) Will display current GLOBAL setting

Cheat Keys:

CTRL + X - Show [x,y] coordinates of mouse and current area in the Dialog window.
CTRL + F : Change Selected face position
CTRL + S/A : Change Selected Animation Sequence
CTRL + I/L : Play Selected Animation effect on Selected
CTRL + C - Display SoA/ToB Epilogue GUI (Do Not Use)
CTRL + J : teleports selected party members to position under cursor
CTRL + Q : auto-recruit creature under cursor into party
CTRL + R : insta-restores any creature under cursor- also removes any effects
CTRL + Y : insta-kills creature under cursor
CTRL + P : Center screen Selected
CTRL + G - Display loaded area ref
CTRL + M/Enter : Display current info about your location
CTRL + N : Freeze screen for 5 seconds
CTRL + 1 - Display Selected Animation armour level
CTRL + 3 - Fade Screen to black
CTRL + 5 - Display Selected current Animation frame/Sequence
CTRL + 6/7 : Change Selected animation

I hijacked some of @KeithS stuff and added more.

2.INI Config Settings

You can disable the colored foot circles by editing your Baldur.ini with this setting:
'Game Options', 'Color Circles', '0',

3.Using Custom Scripts

Custom scripts can be assigned to your character via the 'Customize" button in your Character Sheet.

Modding sites such as G3, SHS and Pocket Plane have scripts that you can download and use for your player.

Navigate to this folder and place your scripts below to use in-game:
\Baldur's Gate Enhanced Edition\Data\00766\scripts

You can also use 'Hotkey' scripts to accomplish single or multiple actions that will save you time.
To use 'Hotkey' scripts:
1 - Assign the script to your character.
2 - Back in game hit the appropriate letter key when you wish to activate the script. Simple.
3 - You can use the key as many times as you like.
4 - When finished, unassign the script via the 'Customize' screen by assigning "None.bs"

For those familiar with compiling BAF to BCS, here are some examples you can paste into your text editor to compile with WeiDU, DLTCEP or NI.
Feel free to grab these and use them, change numbers or resources indicated. Have fun.

Example Cheat/Debug Scripts

Giving Experience to the party or PC

IF
	HotKey(D)
THEN
	RESPONSE #100
		AddexperienceParty(24000)
END

IF
	HotKey(C)
THEN
	RESPONSE #100
		AddXPObject(Player1,5000)
END

Giving Special Abilities

   
IF
	HotKey(D)
THEN
	RESPONSE #100
		AddSpecialAbility("spin101") // Cure Light Wounds
		AddSpecialAbility("spin104") // Larloch's Minor Drain
		AddSpecialAbility("spin105") // Horror
		AddSpecialAbility("spin106") // Vampiric Touch
		DisplayStringHead(Myself,10315) // Ability Bonuses
END

Set Chapter and reveal area on map

   
IF
	HotKey(A)
THEN
	RESPONSE #100
		SetGlobal("Chapter","GLOBAL",4)
		RevealAreaOnMap("AR0900")
		IncrementChapter("Chptxt5")
		AddJournalEntry(15839,USER)
END

Heading to Baldur's Gate via a hotkey cutscene

   
IF
	HotKey(D)
THEN
	RESPONSE #100
		ClearAllActions()
		StartCutSceneMode()
		CutSceneId(Player1)
		FadeToColor([30.0],0)
		Wait(2)
		LeaveAreaLUAPanic("AR0900","",[2830.2330],0)
		LeaveAreaLUA("AR0900","",[2830.2330],0)
		ActionOverride(Player2,LeaveAreaLUA("AR0900","",[2830.2330],0))
		ActionOverride(Player3,LeaveAreaLUA("AR0900","",[2830.2330],0))
		ActionOverride(Player4,LeaveAreaLUA("AR0900","",[2830.2330],0))
		ActionOverride(Player5,LeaveAreaLUA("AR0900","",[2830.2330],0))
		ActionOverride(Player6,LeaveAreaLUA("AR0900","",[2830.2330],0))
		Wait(2)
		MultiPlayerSync()
		FadeFromColor([30.0],0)
		EndCutSceneMode()
END

Anyone can cast a spell

   
IF
	HotKey(D)
THEN
	RESPONSE #100
		ForceSpellRES("SPWI502",NearestEnemyOf(Myself)) // Cloudkill
END

More stuff to come.