While playing, hit ~ to bring up the console. Then type in "DebugMode 1" without the quotes. You may then use the following codes. (Note that all codes are cAsE sEnSiTiVe and some such as the set(stat) codes require you to select a target when you use them)

To open the console on a non-English keyboard (like Swedish for example), press the accentuation (not apostrophe!) and questionmark buttons in quick succession while holding down shift.

In chapter two, after you go through the "trial" and defeat Lorne, you can return to West Harbor to complete the quest "What Happened to Lorne" (you have to have gotten the quest in Chapter One before leaving West Harbor). Talk to Lorne's mother to complete the quest, and you'll get 500 XP. She'll say she needs to be left alone. Now talk to her again. She'll give the intro to the "quest completed" dialog, and give you 500 XP again. Rinse and repeat. (Fixed in 1.03)

When in Ammon Jerro's Haven, if the player learns the true name of Zaxis he is able to command the demon to open the gate. After you open the gate you get 1000 exp. If you talk to him again you will have another option to ask him to stop referring to himself in the third person. After that option is selected the player can once again tell Zaxis to open the portal and gain another 1000 exp. This can be done for an infinite amount of times up until the party leaves Ammon Jerro's Haven (Note: Works in 1.03)