This one is really simple, but a great idea. You can buy baby or pet gates pretty cheap these days, but none of them are custom made for your door frame, which means none of them are quite a perfect fit. Over at the Finding Purpose Blog, one couple was came up with the idea to just make their own. All it really takes is a little wood, a little measuring, and a few hinges. Seriously, that's all there is too it. Check it out here because there's not much more I can say.