Fallout 3

From Wiki Cheat Codes

Xbox 360 & PS3

Cheat: Extra Weapons (in Operation Anchorage) Note: this cheat only applies to the Operation Anchorage downloadable content pack. As soon as you are able to control your own strike team, you'll be able to get specific weapon loadouts from a terminal. If you give these to the Quartermaster, you can go get another loadout. Drop all the new stuff and talk to the Quartermaster. He'll give you your stuff sans ammo. That's no problem though, since you can head to the ammo dispenser for more. Pick up the weapons on the ground when you're ready to go, or repeat for all the weapons you can handle.

Cheat: The 55 Gallon Drum Carryall If you are having trouble carrying with over-encumbrance, this cool trick could help you tote around some extra gear. First go through and clear an area of enemies, then grab (Click the right analog stick) a 55 gallon drum. They are ubiquitous in most areas. Fill up the drum by physically picking up items and dropping them in and you'll have an instant "shopping cart" for all your stuff. You can even fast travel with it -- but when you appear at your destination the drum falls to the ground and you have to pick it all back up again.

Hint: Infinite Good Karma in Megaton Here’s another technique for infinite good karma. If you head to Megaton, you can find the church for the Children of the Atom, religious people who worship the undetonated nuclear bomb which Megaton is built around. There’s a priest who will be near the bomb or in their building. Talk to him and he’ll ask for donations. Give him donations, and you’ll get a positive karma boost. Do this as much as you want for as much karma as you desire.