Recently my son was home on an extended weekend after a deployment with the Marine Corps and we got into a discussion about what guns we'd like to have in our home armory. The discussion soon evolved to be more about what someone SHOULD have versus what they WANT to have. This bore further examination and, because it's easier to keep track of lists on paper, I soon found myself writing out a list of weapons we felt were necessary. Bear in mind, this isn't a "soldier" list, or a "police" list; in our minds, this is an American Citizen list.
A Precision Rifle:
Whether it's a custom built .308 caliber rifle like the Special Projects Unlimited gun shown above right, or an "off the shelf" 7mm (or other usable caliber), the bolt action rifle is a must. Not only are they one of the primary weapons used for hunting game (to put meat on your table) but they are also invaluable as defensive weapons provided your perimeter is far enough away to make use of their strengths. The two bolt-action guns I've used most were both custom built: one, the SPU rifle shown with an 18" barrel, and the other a rifle from Iron Brigade Armory that had a 20" barrel. Both were chambered for .308. There are several good manufacturers of bolt guns and you can usually find one at your local gun store or gun show for under $300. Make sure the caliber is sufficient for your perceived needs.
A Fighting Rifle:
Yes, I am a paranoid person. I do believe that it is inevitable that, at some point in the not too distant future, there's a good chance our country will encounter circumstances which will put families in the position of having to defend their own property, unable to wait or depend on public safety services. When such circumstances occur, the bad guys will most certainly grab the biggest baddest guns they can find and go out hunting for weaker citizens to prey on. In many urban areas, the engagement distances limit your need for a rifle that's effective past 100 to 200 yards, but having one that CAN engage past that is good. The only reason I'd recommend .223 over .308 for this weapon is because of the cost and weight of the ammo. No matter which manufacturer you choose, or if you build your own, make sure you have at least seven high quality high-capacity magazines and a sufficient supply of ammo.
A "Combat" Shotgun:
While a shotgun can most assuredly be used for hunting birds, small game and even larger game if you use the proper loads, its value as a close-quarters defensive weapon shouldn't ever be under-appreciated. With the huge variety of specialty loads that are available for a 12g shotgun and the equally wide variety of after-market custom options that you can install or mount yourself, the versatility of the shotgun is unmatched. Remembering that you need to stay in compliance with your state and local laws I would recommend you examine the possibility of extending your magazine tube. I'd also recommend you look at mounting an 18 or 20 inch barrel. The federal legal minimum length is 18" so be sure you don't go below that. I'd actually recommend 18.25" or 18.5" so there's a clear compliance with that law.
As you read just a tad further you'll see that I recommend two handguns: one pistol and one revolver. The pistol you select must be the proper balance, as you perceive it, of fighting caliber versus sufficient capacity. For more detailed information about selecting a pistol for personal defense check out the article I wrote specifically about that effort (linked in below).
I am a long time fan of the 1911 model of pistol from any of the reputable manufacturers, as well as being a fan of the Glock pistols. That's not to say that other manufacturer's pistols aren't valuable or reliable or any of that. I just "grew up" carrying and shooting a Government Model 1911 .45ACP. When Glock came along in the mid-'80s I thought they were pretty ugly guns, but pretty is as pretty does. Unless you really work to screw them up, Glocks are reliable and will take a fair amount of abuse. 1911s tend to be a bit heavy and unless you get a double-stack wide-gripped version, you're going to be limited to between 7 and 10 rounds in your magazine. So, as I said at the outset, measure your need / beliefs about caliber size vs. magazine capacity and choose wisely.