And for the third mission in the list we have another from early in the game. After leaving Goodsprings you ventured off into the wasteland to discover, survive, and hunt Benny. On the way from Goodsprings to New Vegas, you most likely encountered the motel shanty-town of Novac, I mean, it's pretty hard to miss with that giant dinosaur at the gate.
Despite being one of the smaller towns in the game, Novac is chock full of zany characters, bizarre goings-ons, and great quests. The most important quest of all though is 'One For My Baby' -- which sees you get a companion, assuming you play it properly that is.
So you enter the Dinosaur and go up to the mouth, which is wisely being used as a watchtower. The night guard is a surly guy named Boone, who isn't much of a talker. Eventually you will find out that Boone is pissed because his wife was sold to slavers, and he wants you to find out who in Novac made the deal. Long mission short, you steal the slaver bill of sale from the safe at the front desk of the Dino Dee-Lite motel. Once you find out who sold Boone's wife you can lure them out in front of the dinosaur, wearing Boone's beret so that he knows, and allow him to snipe the persons head off.
Not only is this a very cool mission that involves slave trading, espionage, treachery, and murder, but it results in you getting a companion that can shoot from long-distance.