Baldur's Gate II: Shadows of Amn/Cheats

Infinite EXP
When you are in Brynlaw and need to get into Lady Galenva's palace, first kill surly to get the medallion then go to one of the people outside, you need a high Charisma and probably a high intelligenct to pull this off, then go to their room and convince them to mutiny, go to the cook and get the servant to put the potion in the ale and give it to the guards, then get the key and kill the enemies, now go back to the cook and every time you talk to her, you will get EXP.

Increace stats
To do this, you need to be in Hell, first get one Tear of Bhaal and export the character holding it then make 5 of them holding the tear using the multiplayer screen, use all 5 then export the 1st character (with the effect of 5 tears) and reload then import the previous character (with the effect of the 5 tears) and repeat the process.
 * Requires Multiplayer

Note: The tears will only do the good effect, if you want the evil effect then you have to save after you have completed the task done the evil way. Note to get the AC bonus, you need the expansion pack or get the patch.

Method 1
This will duplicate the item loads of times: Go to the inventory (needs to be paused if in Multiplayer) then drink the potion and then swap the potion and the gem in the inventory. there will now be no number next to the gem, do this again and it will become a ridiculously high number, sell the gems for all the money you will ever need.
 * Needs an expensive gem and a potion

Method 2
First drink a few potions of master thievery then steal all of the items from someone who sells fenced goods, sell them back to them and laugh.
 * Needs a Thief