Ever built a fort when you were a kid? I'm still not sure how cool the Fence Fort stacks compared to our makeshift one, built with Aerosmith and Def Leppard posters (aaah, those were the days), but it does look pretty dandy.
It's basically a tent with one side designed to rest right up on the fence, allowing at least one side of the fort to foster an impenetrable barrier. While it won't be as fun as a tree house, it does give your kids a private space in the backyard that they can call their own (plus, it's not as ghetto as making a fort from a blanket). In case your wife kicks you out of the bedroom, you can even use it to camp out - just make sure to shrivel up your legs when you're sleeping, cause it's probably too small for you.
With the fun half-tent design, I'm pretty certain kids will love the way this fort looks. String three or four of them together and get a large facade that's truly imposing. Made of super strong 210 T Nylon, it allows enough light to get in, so the kids don't have to play in the dark. The fort rests sturdily on the fence by a built-in weighing system, allowing it to stay in place even when the raucous ones start pushing on its sides.
Since setup and disassembly only takes a few seconds each, you can easily fold it up and bring it with you on camping and vacations. Not only can your kids have their fort, but they can take it wherever they go (as long as there's a wall to lean it into). The Fence Fort comes in four different color combinations and is available for $60.