If you have bad karma (or don't mind having even worse karma), head over to Paradise Falls, a place a group of evil slavers call home. To gain entrance without having to open fire, you have to be friendly with the slavers, which will give you an evil slant. But if you can do this, you'll find a guy endlessly walking around the settlement (he's usually at or near the bar, but can be elsewhere). When you get near him, he'll stop you automatically, tell you he found some cool stuff on a recent raid, and give you some of what he got (it will be either some ammunition, Bottle Caps, or various aid items). After your first encounter, all you have to do is keep speaking to him to earn more and more free stuff.