Some of mine, in rough order of occurrence. None of these should affect the story or your ability to do any subsequent quest in any way (unlike, for example, killing the Van Graffs and looting the Silver Rush):
(1) From Goodsprings-- go to Chet's General Store and buy a shovel. Follow the road north until you hit a sign that says "Caution! Go Back!' Turn immediately due west, wand walk up the ridge until you can't go anymore. Go into sneak and turn due north. Follow the wall until you come to a drop. You should see several cazadores circling far below (this is the marked location Tribal Village) . Head a little east along the ridge until you see a grave with two ravens resting nearby. drop down and dig the grave to recover Chance's Knife, the unique combat knife, at 100% condition (along with some Simple Khan Armor). Fast travel out. NOTE: If you have the Mercenary's Grenade Rifle, you might consider clearing out the cazadores in Tribal Village below, as the top of the ridge before you drop to the grave is a relatively safe vantage point. If you can, you'll find 1-2 Fire Axes and several other goodies.
(2) If you have Lonesome Road installed, you have the option of entering and leaving at your pleasure. The entrance is just northwest of the California Sunset Drive-in (between Primm and Mojave Outpost), and guarded by a few Coyotes. There's a trailer near the entrance with several containers, containing a total of 10 Frag Grenades. Enter Lonesome Road and continue into Hopeville Missile Silo. You can complete the first floor of the Silo without encountering any enemies-- If you have at least 25 Science, you can hack a terminal on the second floor to deactivate the security robots. Thus, without engaging in any combat, you can clear out the first two floors, in which you will find (1) an upgrade for ED-E (which affects ED-E outside of Lonesome Road as well) that allows him to repair one of your weapons by a moderate amount for free once per day; (2) two H & H Tools Nailguns (value 5000 each, fully repaired), (3) an Arc Welder (value 3700 at full repair), (4) a Bowie knife (value 1000 fully repaired), and (4) enough duct tape, wrenches, scrap metal, and scrap electronics for a dozen Weapon Repair kits.Use ED-E's menu option to make repair kits (50 Repair needed), and use the kits to repair these weapons. Then sell the weapons at the Commissary for several thousand caps. You can also use the commissary to purchase Riot Armor, a Riot Helmet, and/or US Army Combat Armor, if you feel so inclined. If feeling adventurous, you can continue and fight to the end of the Bunker (buying pulse grenades.mines at the Commissary will help), acquiring 2-3 more Arc Welders, the U.S. Army General's Uniform (+10 Speech, +5 guns), several additional Bowie Knives, and many Missiles and Energy Cells from dispatched robots. If you thoroughly clear this building out, you should walk away with powerful new armor and 12000-18000 caps.
(3) When you arrive at Helios One, head due west, killing a few radscorpions along the way. You stumble upon Black Rock cave, which contains three Nightkin, equipped with (1) a Bumper Sword, (2) an Assault Carbine or Light Machine Gun, and (3) a Heavy Incinerator. After dispatching the Nightkin, loot the dead body of a raider for the unique power fist Paladin Toaster.
(4) Head north to Boulder City. Continue east to find Hoover Dam. Enter the main foyer, immediately on your right. You'll find a snow globe on the desk. Equip the Paladin Toaster and use a Stealth Boy. Proceed to use power-sneak-attack criticals to murder all of the NCR soldiers and Heavy Troopers on the first and second floors. As long as you are not detected, you will lose no Karma and no NCR reputation. Loot the soldiers for several Sniper Rifles, 12.7mm Pistols, and Combat Knives. Loot the three Heavy Troopers for 3 sets of NCR Salvaged Power Armor, 3 Super Sledges, and 3 other weapons, which (depending on your level) will be Incinerators, Hunting Shotguns, Riot Shotguns, or Heavy Incinerators.
(5) Continue north and gain access to Nellis Air Force Base. If you are okay with stealing, this place is a goldmine. The many grey metal boxes in the Hangar contain Combat Armor and Combat Helmets. In the Mess hall & munitions Storage, you'll find a vendor surrounded by high-value Explosives and Missile launchers, along with several additional Combat Armors. If you complete the quest Ant Misbehavin', you'll find two dead boomers with a Marksman Carbine and an Assault Carbine, each resting on he floor next to their corpses, along wihth the unique Grenade rifle Thump-Thump and a considerable amount of .308 and 5mm ammunition and a couple of Mini Nukes in the basemant.
(6) This one also requires theft. Gain access to the Brotherhood of Steel base. Take the first right and head for the shooting range/armory (remember to check the bin on the floor in the medical office for a Nikola Tesla & You). Use a stealth boy and pickpocket Knight Torres for her key. Senak out of the armory and go down the first set of stairs to your right, backtrack, under the floor, into the armory and use the key to unlock the door below Torres. sneak through and up the stairs to steal four full sets of T-45d power armor in excellent condition, a laser rifle, and some energy weapon ammunition.