Fallout: New Vegas

When you want to steal something and it is in the owner's direct line of sight, use the Grab function and drag it around a corner. Use sneak to make sure that you are now hidden from their view. You can now steal the object without fear of retaliation. You will still lose karma but they will not try to kill you.

When you have more than one type of ammunition for a gun (for example, 9mm or 9mm hollow point), press Up and your character will switch ammo types for that weapon.

Thump-Thump is found in the location where all the ants are found, underneath the solar panels when you help the Boomers. It is a grenade launcher.

Search the indicated locations to find all unique weapons:

.357 Magnum Revolver - Lucky: In Primm at The Bison Steve Hotel, in a floor safe (requires 75 Lockpick skill level) behind the cash register of the Gift Shop (northeast room).
.44 Magnum Revolver - Mysterious Magnum: Owned by the Lonesome Drifter, by the Sunset Sasparilla Billboard, close to El Dorado Dry Lake.
9 Iron - Nephi's Golf Driver: Carried by a Fiend named Driver Nephi, in his territory.
9mm Pistol - Maria: On Benny, when you kill him.
9mm Submachine Gun - Vance's Submachine Gun: In Win's Hideout, inside the safe.
Alien Blaster: At the Hovering Anomaly.
BB Gun - Abilene Kid LE BB Gun: Inside the Fiend's Shack, lying on a shelf.
Bladed Gauntlet - Cram Opener: In Camp McCarran, owned by Little Buster.
Boxing Gloves - Golden Gloves: Inside Lucky 38 Casino, on the upper bar of the casino floor.
Bumper Sword - Blade Of The East: In Legate's Camp, carried by Legate Lanius.
Cleaver - Chopper: On the stove of Wolfhorn Ranch.
Combat Knife - Chance’s Knife: In Chance's Grave.
Cowboy Repeater - La Longue Carabine: In Camp McCarran, carried by Corporal Sterling, whom you must kill to get it.
Displacer Glove - Pushy: Inside the Ruby Hill Mine, on the body of a Jackal Gang member.
DogTag Fist - Recompense Of The Fallen: In Aurelius' desk, on the upper floor of the main building in Cottonwood Cove.
Euclid's C-Finder: On the Freeside Streets, carried by Max, in and around Nick and Ralph's.
Fat Man: In Quarry Junction, near the skeleton by the southern silt pool. It is also occasionally found on prospector corpses.
Fire Axe - Knock Knock: In the Camp Searchlight Fire Station, in the restrooms.
Frag Grenade - Holy Frag Grenade: In Camp Searchlight, in the basement of the eastern church. Note: Wild Wastleland trait is required.
Gauss Rifle - YCS/186: At the Mercenary Camp; Wild Wasteland trait must not be taken.
Grenade Machine-gun - Mercy: On the floor of Dead Wind Cavern, near a dead BoS Paladin.
Grenade Rifle - Thump-Thump: At the Nellis Array, lying on the floor near the Ant mound.
Hunting Shotgun - Dinner Bell: At The Thorn, in the sewers in front of Westside. You must complete the "Bleed Me Dry" quest given by Red Lucy.
Laser Pistol - Pew Pew: After completing "The Legend Of The Star" quest, it will be on the body of Allen Marks.
Laser Rifle - AER14 Prototype: Inside the Vault 22 Common Area, on the blocked stairwell only accessible from the fifth level (Pest Control).
Lead Pipe - The Humble Cudgel: Inside the Sealed Sewers, near the Prospector Corpse.
Machete - Liberator: In Nelson, carried by Dead Sea.
Minigun - CZ57 Avenger: In the Devil's Throat, inside, at the back of the container trailer, by the dead body.
Missile Launcher - Annabelle: In Black Rock Mountain, carried by the Nightkin Sniper on Black Rock Summit, whom you must kill to get it.
Marksman Carbine - All-American: In the Armory Cache, Vault 34, on the floor, on an upturned table.
Oh, Baby!: In the deepest part of Charleston Cave, near a Chewed Stealth Boy.
Plasma Rifle - Q-35 Matter Modulator: In the locked shipping room of REPCONN HQ, in a pod casement.
Pulse Gun: In the Armory Cache, Vault 34.
Sawed-Off Shotgun - Big Boomer: In Gibson Scrap Yard, carried by Old Lady Gibson, whom you must kill to get it.
Sniper Rifle - Gobi Campaign Scout Rifle: In the footlocker of the Sniper's Nest, overlooking the Cottonwood Cove.
Spiked Knuckles - Love and Hate: In Bonnie Springs, on the Viper Gang Leader.
Straight Razor - Figaro: In the back of King's School Of Impersonation, owned by Sergio, whom you must kill to get it.
Tesla Cannon - Tesla-Beaton Prototype: On the ground near the crashed Vertibird.
That Gun: In Novac, on a shelf in the locked storage room inside the Dino Bite Gift Shop.
This Machine: At the end of the "Dealing With Contreras" quest, it will be a reward from Contreras for not turning him in.
Varmint Rifle - Ratslayer: Inside the Broc Flower Cave, propped up against the desk.
Zap Glove - Paladin Toaster: In Black Rock Cave, near the body of the dead prospector.

In Guardian Peak you will meet an NCR soldier who is wounded. Through some Speech checks, you can get him to give you his gun for escorting him out of the cave that he is in. When you get to the entrance of the cave with him in tow, he will speak and you can continually ask for his rifle, which he will give you along with ammunition. Note: This is best done after earning the perk that allows for over encumbered fast travel.

Note: This requires the unpatched version of the game. Begin going through the storyline, once you get to Prim and complete the quest there, leave for awhile and return. You will be able to gamble. In order to gamble you must purchase chips. Go to the cashier at the Vikki & Vance Casino. Purchase as many chips as possible with any of the three types of money (Caps, NCR, and Legionaries). Once you have the chips, save the game normally (not by auto-save). Note: Each chip is worth one cap, so you can trade all the chips back for a full refund if needed. Once your game is saved, talk to the cashier again and select the fourth option (something similar to "Cash in my chips"). She will ask what form of payment you want. Pick any option desired, then quickly exit the conversation. This should have given you as much of the form of money you requested that equals to chips. Caps are 1 chip to 1 cap. NCR are 8 chips to $20 and 40 chips to $100, and Legionaries are 4 chips to one Denarius, 20 chips for a Dalhali, and 100 chips for a Aureus. Once you have exited the conversation, check your inventory. You should have the money and the chips still in your possession. Talk to the cashier and repeat the trick. If you want to get higher amounts at a time, do the trick with caps a few times, then buy 1,000 chips for 1,000 caps about five or six times.

After completing the Sexbot quest, go to the atomic wrangler and talk to Fisto. Choose the "Maybe later" response to get 10 caps. You can continue to do this as many times as desired. With enough time and patience you can accumulate a large amount of caps.

Go to any salesman and press Select. Wait one hour to force an auto save. Go the "Memory" option in the system menu, then select "Hard Drive" and find the auto save file. Copy it to a memory card. Go to your memory card and copy it back to the hard drive. Load the game and start. You should be at the salesman. Do not buy or sell anything yet. Wait one hour to force another auto save. Quit and start the game again. Sell or buy anything. Wait one hour, quit, and start over. The salesman's inventory and money will have reset. Repeat the process as many times as desired.

Note: This requires at least a 35 Medicine skill. Once your character gains access to the main strip, find Victor outside the Lucky 38 casino. He will tell you that Mr. House wants to meet you. Follow him inside and go up the elevator. Speak with Mr. House (the giant television face that looks like Howard Hughes). Find the dialogue choice pertaining to needing to ask him a few questions. Then, ask "Who exactly are you, Mr. House?", then select "You appear to be a computer, not a man". After that, select the Medicine skill check response, "The lifespan you're claiming is impossible, except for ghouls and super mutants." After that, you will be awarded 35 experience points (or 39 experience points if you have the Swift Learner perk). You can repeat this as many times as desired.

This trick yields unlimited experience, Stimpacks and doctor's bags. Get access to Helios One Power Station and have the quest "That Lucky Old Sun". When you have the option to choose how to reroute the power, select to do full region (emergency output level). Go out and re-aim the solar array panels, then return to Ignacio. Tell him you overpowered the station. He will reward you with 350 experience points, three Stimpacks, and two doctor's bags. The option will remain in place allowing you to do this repeatedly as many times as desired.

Upon meeting Mr. House the first time, in "The House Always Wins, I" mission, he will ask you to get his chip. If you have 50 Barter when he tells you the deal is 1,000 caps, refuse it. Keep refusing his offers after bartering until he tells you to come back. After you talk to him again, select the following choices: "Tell me your terms again?", then the Barter 50 choice "The chip is worth far more than that", then "Still not interested", and repeat.